Objectification of posture state-responsive therapy based on patient therapy adjustments

ABSTRACT

The disclosure describes techniques for objectification of posture state-responsive therapy based on patient therapy adjustments. The techniques may include sensing posture states of a patient, delivering posture-state responsive electrical stimulation therapy to the patient based on the sensed posture states, receiving patient adjustments to the electrical stimulation therapy delivered to the patient, determining a number of the patient adjustments received over a time interval, and presenting a representation of the number of the patient adjustments received over the time interval to a user.

This application claims the benefit of U.S. provisional application No.61/080,000, filed Jul. 11, 2008, the entire content of which isincorporated herein by reference.

TECHNICAL FIELD

The disclosure relates to medical devices and, more particularly, toprogrammable medical devices that deliver therapy.

BACKGROUND

A variety of medical devices are used for chronic, e.g., long-term,delivery of therapy to patients suffering from a variety of conditions,such as chronic pain, tremor, Parkinson's disease, epilepsy, urinary orfecal incontinence, sexual dysfunction, obesity, or gastroparesis. Asexamples, electrical stimulation generators are used for chronicdelivery of electrical stimulation therapies such as cardiac pacing,neurostimulation, muscle stimulation, or the like. Pumps or other fluiddelivery devices may be used for chronic delivery of therapeutic agents,such as drugs. Typically, such devices provide therapy continuously orperiodically according to parameters contained within a program. Aprogram may comprise respective values for each of a plurality ofparameters, specified by a clinician.

In some cases, the patient may be allowed to activate and/or modify thetherapy delivered by the medical device. For example, a patient may beprovided with a patient programming device. The patient programmingdevice communicates with a medical device to allow the patient toactivate therapy and/or adjust therapy parameters. For example, animplantable medical device (IMD), such as an implantableneurostimulator, may be accompanied by an external patient programmerthat permits the patient to activate and deactivate neurostimulationtherapy and/or adjust the intensity of the delivered neurostimulation.The patient programmer may communicate with the IMD via wirelesstelemetry to control the IMD and/or retrieve information from the IMD.

SUMMARY

In general, the disclosure provides a method and system for generatingand presenting posture state-related information to a user via a userinterface of a patient or clinician programmer. The posturestate-related information may be presented to support objectification ofefficacy of posture state-responsive therapy to a patient. The posturestate-related information may include a variety of information such assleep quality information, proportional posture information, andquantified therapy adjustments made by the patient. Information obtainedbased on posture state data from short therapy sessions may be rejectedin generating the posture state-related information to avoid the use ofunreliable data.

In one example, the disclosure provides a method comprising obtainingposture state data sensed by a medical device for a patient, generatingsleep quality information based on lying posture state changes indicatedby the posture state data, and presenting the sleep quality informationto a user via a user interface.

In another example, the disclosure provides a system comprising aprocessor that obtains posture state data sensed by a medical device fora patient, and generates sleep quality information based on lyingposture state changes indicated by the posture state data, and a userinterface that presents the sleep quality information to a user.

In another example, the disclosure provides a device comprising atelemetry interface, a processor that obtains posture state data sensedby an implantable medical device via the telemetry interface, andgenerates sleep quality information based on lying posture state changesindicated by the posture state data, and a user interface that presentsthe sleep quality information to a user.

In another example, the disclosure provides a method comprisingobtaining posture state data sensed by a medical device for a patientduring delivery of therapy by the medical device, determining durationsfor which the patient occupied each of a plurality of posture statesbased on the posture state data, generating proportional postureinformation for a plurality of different time intervals based on thedurations, wherein the proportional posture information for each of thetime intervals indicates proportional amounts of the respective timeinterval in which the patient occupied the posture states, andpresenting the proportional posture information to a user via a userinterface.

In another example, the disclosure provides a system comprising aprocessor that obtains posture state data sensed by a medical device fora patient during delivery of therapy by the medical device, determinesdurations for which a patient occupied each of a plurality of posturestates based on the posture state data, and generates proportionalposture information for a plurality of different time intervals based onthe durations, wherein the proportional posture information for each ofthe time intervals indicates proportional amounts of the respective timeinterval in which the patient occupied the posture states, and a userinterface that presents the proportional posture information to a user.

In another example, the disclosure provides a device comprising atelemetry interface, a processor that obtains, via the telemetryinterface, posture state data sensed by a medical device for a patientduring delivery of therapy by the medical device, determines durationsfor which a patient occupied each of a plurality of posture states basedon the posture state data, and generates proportional postureinformation for a plurality of different time intervals based on thedurations, wherein the proportional posture information for each of thetime intervals indicates proportional amounts of the respective timeinterval in which the patient occupied the posture states, and a userinterface that presents the proportional posture information to a user.

In another example, the disclosure provides a method comprisingaccumulating posture state data sensed by a medical device for a patientduring therapy sessions between successive programming sessions of themedical device, wherein the medical device delivers therapy to thepatient during each of the therapy sessions, determining durations forwhich the patient occupied each of a plurality of posture states duringthe therapy sessions based on the posture state data, wherein lengths ofat least some of the therapy sessions are different, generatingproportional posture information for the therapy sessions based on thedurations, wherein the proportional posture information indicates, foreach of the therapy sessions, proportional amounts of the respectivetherapy session in which the patient occupied the posture states, andpresenting the proportional posture information to a user via a userinterface.

In another example, the disclosure provides a method comprising sensingposture states of a patient, delivering posture-state responsiveelectrical stimulation therapy to the patient based on the sensedposture states, receiving patient adjustments to the electricalstimulation therapy delivered to the patient, determining a number ofthe patient adjustments received over a time interval, and presenting arepresentation of the number of the patient adjustments received overthe time interval to a user.

In another example, the disclosure provides a system comprising a sensorthat senses posture states of a patient, a stimulation generator thatdelivers posture-state responsive electrical stimulation therapy to thepatient based on the sensed posture states, an input device thatreceives patient adjustments to the electrical stimulation therapydelivered to the patient, a processor that determines a number of thepatient adjustments received over a time interval, and a user interfacethat presents a representation of the number of the patient adjustmentsreceived over the time interval to a user via a user interface.

In another example, the disclosure provides a method comprising storingposture state data sensed by a medical device for a patient, rejectingany portion of the posture state data that was stored during a sessionthat was shorter than a session threshold, and generating posture stateoutput for the patient based on a portion of the posture state data thatwas not rejected.

In another example, the disclosure provides a system comprising a memorythat stores posture state data sensed by a medical device for a patient,and a processor that rejects any portion of the posture state data thatwas stored during a session that was shorter than a session threshold,and generates posture state output for the patient based on a portion ofthe posture state data that was not rejected.

The details of one or more aspects of the disclosure are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages will be apparent from the description anddrawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a conceptual diagram illustrating an implantable stimulationsystem including two implantable stimulation leads.

FIG. 1B is a conceptual diagram illustrating an implantable stimulationsystem including three implantable stimulation leads.

FIG. 1C is a conceptual diagram illustrating an implantable drugdelivery system including a delivery catheter.

FIG. 2 is a conceptual diagram illustrating an example patientprogrammer for programming stimulation therapy delivered by animplantable medical device.

FIG. 3 is a conceptual diagram illustrating an example clinicianprogrammer for programming stimulation therapy delivered by animplantable medical device.

FIG. 4 is a functional block diagram illustrating various components ofan implantable electrical stimulator.

FIG. 5 is a functional block diagram illustrating various components ofan implantable drug pump.

FIG. 6 is a functional block diagram illustrating various components ofan external programmer for an implantable medical device.

FIG. 7 is a block diagram illustrating an example system that includesan external device, such as a server, and one or more computing devicesthat are coupled to an implantable medical device and externalprogrammer shown in FIGS. 1A-1C via a network.

FIGS. 8A-8C are conceptual diagrams illustrating definition anddetection of a posture state of a patient based on signals sensed by aposture state sensor.

FIG. 9 is a conceptual diagram illustrating an example user interface ofa patient programmer for delivering therapy information to the patient.

FIG. 10 is a conceptual diagram illustrating an example user interfaceof a patient programmer for delivering therapy information that includesposture information to the patient.

FIG. 11 is a conceptual diagram illustrating an example user interfacefor presenting graphical proportional posture information to a user fordifferent time intervals, such as days.

FIG. 12 is a conceptual diagram illustrating an example user interfacefor presenting detailed posture state durations for each time intervalof FIG. 11.

FIG. 13A is a conceptual diagram illustrating an example user interfacefor presenting graphical proportional posture information averaged forseveral larger time intervals, such as weeks or months.

FIG. 13B is a conceptual diagram illustrating an example user interfacefor presenting detailed posture state durations for each time intervalof FIG. 13A.

FIG. 14A is a conceptual diagram illustrating an example user interfacefor presenting graphical proportional posture information for previoustherapy sessions.

FIG. 14B is a conceptual diagram illustrating an example user interfacefor presenting detailed posture state durations of upright posturestates and lying posture states.

FIG. 15 is a conceptual diagram illustrating an example user interfacefor presenting graphical proportional posture information in addition toa posture state frequency value for each posture state.

FIG. 16A is a conceptual diagram illustrating an example user interfacefor presenting an average quantified number of posture changes duringselected time intervals of therapy.

FIG. 16B is a flow diagram illustrating an example method for presentingan average quantified number of posture changes during selected timeintervals of therapy.

FIG. 17 is a conceptual diagram illustrating an example user interfacefor presenting sleep quality information as a graph of the quantifiednumber of posture state changes when the patient is lying down.

FIG. 18 is a conceptual diagram illustrating an example user interfacefor presenting details on the number of times the patient moved betweeneach posture state during sleep.

FIG. 19 is a conceptual diagram illustrating an example user interfacefor presenting the average number of posture state changes when thepatient is lying down for a given time interval.

FIG. 20 is a conceptual diagram illustrating an example user interfacefor presenting detailed information on the average number of times thepatient left each lying posture.

FIG. 21 is a conceptual diagram illustrating an example user interfacefor presenting an average number of posture state changes when thepatient is lying down during each therapy session.

FIG. 22 is a flow diagram illustrating an example method for presentingproportional posture information to the user from recently storedposture state data.

FIG. 23 is a flow diagram illustrating an example method for presentingspecific posture state information to the user on the proportionalposture graph.

FIG. 24 is a flow diagram illustrating an example method for presentingsleep quality information derived from the posture state data.

FIG. 25 is a flow diagram illustrating an example method for rejectingraw posture state data stored during a therapy session shorter than asession duration.

FIG. 26A is a conceptual diagram illustrating an example user interfacefor presenting a graph that displays the number of initial therapyadjustments that a patient makes when entering into a different posturestate.

FIG. 26B is a conceptual diagram illustrating an example user interfacefor presenting a graph that displays the number of therapy adjustmentsthat a patient makes while occupying a posture state.

FIG. 26C is a conceptual diagram illustrating an example user interfacefor presenting a graph that displays an average number of therapyadjustments that a patient makes each time the patient occupies aposture state during a time interval.

FIG. 26D is a conceptual diagram illustrating an example user interfacefor presenting a graph that displays a total number of therapyadjustments that a patient makes for all posture states during a timeinterval.

FIG. 27 is a conceptual diagram illustrating an example user interfacefor presenting a table that displays the number of therapy adjustmentsthe patient makes when entering into a different posture state.

FIG. 28A is a flow diagram illustrating an example method for presentingthe number of initial therapy adjustments made in response to entering anew posture state.

FIG. 28B is a flow diagram illustrating an example method for presentingthe number of therapy adjustments that a patient makes while occupying aposture state.

FIG. 29 is a conceptual diagram illustrating an example posture searchtimer and posture stability timer when a patient remains in one posturestate.

FIG. 30 is a conceptual diagram illustrating an example posture searchtimer and posture stability timer with one change in posture state.

FIG. 31 is a conceptual diagram illustrating an example posture searchtimer and posture stability timer with two changes in posture states.

FIG. 32 is a conceptual diagram illustrating an example search timer andposture stability timer with the last posture state change occurringoutside of the posture search timer.

FIG. 33 is a flow diagram illustrating an example method for associatinga received therapy adjustment with a posture state.

DETAILED DESCRIPTION

In some medical devices that deliver electrical stimulation therapy,therapeutic efficacy may change as the patient changes posture statesthroughout the daily routine of the patient. In general, a posture statemay refer to a patient posture or a combination of posture and activity.For example, some posture states, such as upright, may besub-categorized as upright and active or upright and inactive. Otherposture states, such as lying down posture states, may or may not havean activity component. Efficacy may refer, in general, to a combinationof complete or partial alleviation of symptoms alone, or in combinationwith a degree of undesirable side effects.

Changes in posture state may cause changes in efficacy due to changes indistances between electrodes or other therapy delivery elements, e.g.,due to temporary migration of leads or catheters caused by forces orstresses associated with different postures, or from changes incompression of patient tissue in different posture states. Also, posturestate changes may present changes in symptoms or symptom levels, e.g., apain level of the patient. To maintain therapeutic efficacy, it may bedesirable to adjust therapy parameters based on different posturesand/or activities engaged by the patient to maintain effectivestimulation therapy. Therapy parameters may be adjusted directly, e.g.,manual adjustment of one or more stimulation parameters, or by selectingdifferent programs or groups of programs defining different sets oftherapy parameters.

A change in efficacy due to changes in posture state may require thepatient to continually manage therapy by manually adjusting certaintherapy parameters, such as amplitude, pulse rate, pulse width, orelectrode combinations, or selecting different therapy programs toachieve more efficacious therapy throughout many different posturestates. In some cases, a medical device may employ a posture statedetector that detects the patient posture state. The medical device mayautomatically adjust therapy parameters in response to different posturestates, thereby providing posture state-responsive therapy. Therapyadjustments in response to different posture states may be fullyautomatic, semi-automatic in the sense that a user may provide approvalof proposed changes, or user-directed in the sense that the patient maymanually adjust therapy based on the posture state indication.

During stimulation therapy or diagnostic monitoring, the patient may beengaged or desire to be engaged in different posture states, e.g.,postures and activities. The patient may avoid or occupy less time incertain posture states because a particular condition may cause pain,discomfort, or the inability to assume some posture states. A system maybe configured to sense when the patient is in each posture state, storeposture state-related information, and present the posture state-relatedinformation to a clinician or patient as objective data related to thecondition of the patient.

This disclosure is directed to presenting posture state data tofacilitate analysis of the patient's posture states, therapyadjustments, and evaluation of the effectiveness of a therapy currentlydelivered to the patient, such as a posture state-responsive therapy. Insome cases, presentation of posture state data as described in thisdisclosure may aid a clinician in adjusting therapy parameter values toimprove therapeutic efficacy. Symptoms caused by many differentdiseases, disorders or conditions, e.g., chronic pain, tremor,Parkinson's disease, epilepsy, urinary or fecal incontinence, sexualdysfunction, obesity, or gastroparesis, can affect the postures andactivities in which the patient chooses to engage. By monitoring thepatient's posture and activity, a user, e.g., a clinician, may be ableto objectively identify troublesome postures and activities in additionto trends that show improvements or degradations in therapy efficacy.

An implantable medical device (IMD) implanted within the patient mayinclude a posture state module containing a posture state sensor capableof sensing the posture state of the patient. The posture state mayinclude a specific posture of the patient and/or the specific activityconducted by the patient. After the posture state is sensed or detected,that posture state may be stored within the memory as part of theoverall posture state data of the IMD or other device for laterretrieval and review. The IMD may store each different posture stateengaged by the patient, the posture duration of each posture state, thenumber of transitions, i.e., changes, between each posture state as thepatient moves, or any other posture state data derived from the posturestate sensor. In this manner, the IMD may store a posture state historyfor retrieval and analysis.

The user may review the posture state data to objectively determine thepatient's condition and, in some cases, evaluate possible modificationsto therapy parameters. The user may prefer to organize the posture statedata as sleep quality information or proportional posture information tomore easily analyze the posture state data. The sleep qualityinformation and proportional posture information may be presentednumerically graphically as a chart or graph, in addition or as analternative to presentation of the information as quantified values forthe duration of each posture state or number of posture statetransitions during a time interval, either as an absolute value or onaverage.

For example, the sleep quality information may be presented as a sleepquality chart or graph that graphically and numerically indicates theaverage number of posture state transitions while the patient is lyingdown during one or more time intervals. A sleep quality graph thatgraphically and/or numerically displays the sleep quality informationmay allow the user to quickly identify objective data and possibletrends that may provide insight into therapy parameters that provideeffective therapy to the patient. The time intervals may be therapysessions during which therapy is delivered. Each therapy session may bea period of time between successive programming session in which amedical device is programmed to deliver therapy, such as posturestate-responsive therapy. The terms “posture state transitions” and“posture state changes” may be used generally on an interchangeablebasis in this disclosure. The chart may show that more recent monthsshow fewer posture state changes during lying down to indicate, forexample, that recent stimulation therapy may be more effective intreating the patient's chronic pain.

In addition, or alternatively, proportional posture information may bepresented numerically or graphically as an average percentage of timethe patient engages in different posture states, such as lying, upright,and active posture states, for different time intervals, such as aseries of therapy sessions. For each therapy session, a medical devicemay apply therapy parameters specified in a programming sessions. Bycomparing posture state results for different therapy sessions, it maybe possible to observe an efficacy trend resulting from application ofdifferent therapy parameters. If more recent time intervals show thatthe patient is engaged in more upright and active posture states, thenthe user may infer that stimulation therapy, e.g., posturestate-responsive therapy, is being effective in treating the patient'scondition. In particular, upright and active posture states may beassociated with more patient activity than lying posture states. Agreater proportion of time spent in active or upright postures mayindicate efficacy of parameters applied in therapy sessions associatedwith the respective time intervals.

Generally, the sleep quality information and proportional postureinformation may be presented to a clinician via a clinician programmeror another programming or viewing device. The clinician may then monitorthe therapy, sleep quality information, and/or proportional postureinformation to recognize any trends in the patient condition, e.g.,during delivery of posture state-responsive therapy to the patient. Theclinician may view the information when the patient comes in for aclinic visit or remotely via a networked connection between the patientprogrammer and an external device. Alternatively, the patient may viewthe sleep quality information and proportional posture information tomonitor their progress due to therapy or view the monitored posturestate data. In any case, presenting the sleep quality information and/orproportional posture information to a user, such as a clinician orpatient, may allow for more objective posture state monitoring thancould be provided by manual patient logging or periodic patient surveysof subjective pain, activity, posture or other information.

In addition, the system may generate and present a number of posturestate adjustments during the one or more time intervals, such as therapysessions. In each therapy session, a medical device may apply therapy,such as posture state-responsive therapy, according to therapyparameters specified by a clinician in a previous programming session,e.g., in-clinic or remote. The posture state adjustments may provide anindication of efficacy of such parameters. In some cases, the number ofposture state adjustments may be an average number of adjustments foreach posture state over one or more time intervals, such as one or moretherapy sessions. The number of posture state adjustments may indicatethe effectiveness of a stimulation therapy, such as a posturestate-responsive therapy, in allowing the patient to conduct variousactivities. More posture state adjustments, or changes from one posturestate to another, may suggest that the patient is able to be more activebecause the stimulation therapy is suppressing prior pain symptoms. Theposture state adjustments may be presented graphically, numerically, orconcurrently on the same screen of the user interface.

The system also may generate and present a number of patient therapyadjustments during one or more time intervals, such as therapy sessions.Again, in each therapy session, a medical device may apply therapy, suchas posture state-responsive therapy, according to therapy parametersspecified by a clinician in a previous programming session, e.g.,in-clinic or remote. The patient therapy adjustments may provide anindication of efficacy of such parameters. For example, if the patientmakes few adjustments to therapy parameters, it may be inferred thatcurrent therapy parameters are generally effective in addressing thepatient's condition. If the patient makes more numerous therapyadjustments, however, the current therapy parameters may requiremodification to enhance efficacy.

The number of patient therapy adjustments may be indicated forparticular posture states. For example, a medical device may track thenumber of adjustments by the patient upon entering a particular posturestate, possibly with the use of an adjustment timer that tracks thenumber of adjustments within a particular period of time followingsensing of transition to a new posture state. In some cases, the numberof posture state adjustments may be an average number of patient therapyadjustments for each posture state over one or more time intervals. Thenumber of patient therapy adjustments may indicate the effectiveness ofa stimulation therapy, such as a posture state-responsive therapy. Morepatient therapy adjustments may suggest that the patient is havingrelatively greater difficulty in finding suitable therapy parametersettings. The number of therapy adjustments may be presentedgraphically, numerically, or concurrently for one posture state ormultiple posture states, and for one time interval or multiple timeintervals, on the same screen of the user interface.

Whether the system generates sleep quality information, proportionalposture information, posture state change information, patient therapyadjustment information, or any other type of posture state information,it may not be necessary to use all stored posture state data to generatethe information. Use of posture state data sensed and stored during veryshort time intervals, such as very short therapy sessions, may not bedesirable because this data may skew the remainder of the posture statedata. A therapy session generally refers to any therapy duration, e.g.,a time between successive programming sessions which may be associatedwith clinic visits, the time between changes in therapy parameter valuesof programs or groups, the overall time therapy was turned on during anygiving time interval, or any other measure of a therapy duration. Insome cases, a therapy session may be a time between successiveprogramming sessions, which may include in-clinic or remote programmingsessions.

In general, in generating posture state output, a programmer or IMD mayreject any portion of the posture state data that was stored during asession that was shorter than a session threshold. For example, anyposture state data stored when less than twenty four hours elapsedbetween programming sessions, e.g., between clinician visits by thepatient, may be rejected because of this short therapy session. In aprogramming sessions associated with a clinician visit, or in a remoteprogramming session, the clinician may make substantial adjustments totherapy parameter values to be delivered by the medical device during atherapy session. Posture state information obtained when therapyparameter values are applied for only a short period of time may be lessreliable and useful than posture state information obtained for therapyparameter values applied over a longer period of time. In some cases, ashort therapy session may result when the clinician is interruptedduring a programming session. The resulting programming may beincomplete or otherwise not ideal, but therapy may be delivered for ashort period of time until the clinician can initiate anotherprogramming session to complete the programming. To avoid addingunreliable data from the short session, or possibly overwriting gooddata with new data from the short therapy session, posture stateinformation obtained during the short therapy session can be rejected,e.g., discarded rather than stored.

FIG. 1A is a schematic diagram illustrating an implantable stimulationsystem 10 including a pair of implantable electrode arrays in the formof stimulation leads 16A and 16B. Although the techniques described inthis disclosure may be generally applicable to a variety of medicaldevices including external and implantable medical devices (IMDs),application of such techniques to IMDs and, more particularly,implantable electrical stimulators such as neurostimulators will bedescribed for purposes of illustration. More particularly, thedisclosure will refer to an implantable spinal cord stimulation (SCS)system for purposes of illustration, but without limitation as to othertypes of medical devices.

As shown in FIG. 1A, system 10 includes an IMD 14 and externalprogrammer 20 shown in conjunction with a patient 12. In the example ofFIG. 1A, IMD 14 is an implantable electrical stimulator configured forspinal cord stimulation (SCS), e.g., for relief of chronic pain or othersymptoms. Again, although FIG. 1A shows an implantable medical device,other embodiments may include an external stimulator (not shown), e.g.,with percutaneously implanted leads. Stimulation energy is deliveredfrom IMD 14 to spinal cord 18 of patient 12 via one or more electrodesof implantable leads 16A and 16B (collectively “leads 16”). In someapplications, such as spinal cord stimulation (SCS) to treat chronicpain, the adjacent implantable leads 16 may have longitudinal axes thatare substantially parallel to one another.

Although FIG. 1A is directed to SCS therapy, system 10 may alternativelybe directed to any other condition that may benefit from stimulationtherapy. For example, system 10 may be used to treat tremor, Parkinson'sdisease, epilepsy, urinary or fecal incontinence, sexual dysfunction,obesity, or gastroparesis. In this manner, system 10 may be configuredto provide therapy taking the form of deep brain stimulation (DBS),pelvic floor stimulation, gastric stimulation, or any other stimulationtherapy. In addition, patient 12 is ordinarily a human patient.

Each of leads 16 may include electrodes (not shown in FIG. 1), and theparameters for a program that controls delivery of stimulation therapyby IMD 14 may include information identifying which electrodes have beenselected for delivery of stimulation according to a stimulation program,the polarities of the selected electrodes, i.e., the electrodeconfiguration for the program, and voltage or current amplitude, pulserate, and pulse width of stimulation delivered by the electrodes.Delivery of stimulation pulses will be described for purposes ofillustration. However, stimulation may be delivered in other forms suchas continuous waveforms. Programs that control delivery of othertherapies by IMD 14 may include other parameters, e.g., such as dosageamount, rate, or the like for drug delivery.

In the example of FIG. 1A, leads 16 carry one or more electrodes thatare placed adjacent to the target tissue of the spinal cord. One or moreelectrodes may be disposed at a distal tip of a lead 16 and/or at otherpositions at intermediate points along the lead. Leads 16 may beimplanted and coupled to IMD 14. Alternatively, as mentioned above,leads 16 may be implanted and coupled to an external stimulator, e.g.,through a percutaneous port. In some cases, an external stimulator maybe a trial or screening stimulation device that is used on a temporarybasis to evaluate potential efficacy to aid in consideration of chronicimplantation for a patient. In additional embodiments, IMD 14 may be aleadless stimulator with one or more arrays of electrodes arranged on ahousing of the stimulator rather than leads that extend from thehousing.

The stimulation may be delivered via selected combinations of electrodescarried by one or both of leads 16. The target tissue may be any tissueaffected by electrical stimulation energy, such as electricalstimulation pulses or waveforms. Such tissue may include nerves, smoothmuscle, and skeletal muscle. In the example illustrated by FIG. 1A, thetarget tissue is spinal cord 18. Stimulation of spinal cord 18 may, forexample, prevent pain signals from traveling through the spinal cord andto the brain of the patient. Patient 12 may perceive the interruption ofpain signals as a reduction in pain and, therefore, efficacious therapyresults.

The deployment of electrodes via leads 16 is described for purposes ofillustration, but arrays of electrodes may be deployed in differentways. For example, a housing associated with a leadless stimulator maycarry arrays of electrodes, e.g., rows and/or columns (or otherpatterns), to which shifting operations may be applied. Such electrodesmay be arranged as surface electrodes, ring electrodes, or protrusions.As a further alternative, electrode arrays may be formed by rows and/orcolumns of electrodes on one or more paddle leads. In some embodiments,electrode arrays may include electrode segments, which may be arrangedat respective positions around a periphery of a lead, e.g., arranged inthe form of one or more segmented rings around a circumference of acylindrical lead.

In the example of FIG. 1A, stimulation energy is delivered by IMD 14 tothe spinal cord 18 to reduce the amount of pain perceived by patient 12.As described above, IMD 14 may be used with a variety of different paintherapies, such as peripheral nerve stimulation (PNS), peripheral nervefield stimulation (PNFS), DBS, cortical stimulation (CS), pelvic floorstimulation, gastric stimulation, and the like. The electricalstimulation delivered by IMD 14 may take the form of electricalstimulation pulses or continuous stimulation waveforms, and may becharacterized by controlled voltage levels or controlled current levels,as well as pulse width and pulse rate in the case of stimulation pulses.

In exemplary embodiments, IMD 14 delivers stimulation therapy accordingto one or more programs. A program defines one or more parameters thatdefine an aspect of the therapy delivered by IMD 14 according to thatprogram. For example, a program that controls delivery of stimulation byIMD 14 in the form of pulses may define a voltage or current pulseamplitude, a pulse width, a pulse rate, and an electrode combination(e.g., combination of electrodes and polarities) for stimulation pulsesdelivered by IMD 14 according to that program. Moreover, therapy may bedelivered according to multiple programs, wherein multiple programs arecontained within each of a plurality of groups.

Each program group may support an alternative therapy selectable bypatient 12, and IMD 14 may deliver therapy according to the multipleprograms. IMD 14 may rotate through the multiple programs of the groupwhen delivering stimulation such that numerous conditions of patient 12are treated. As an illustration, in some cases, stimulation pulsesformulated according to parameters defined by different programs may bedelivered on a time-interleaved basis or other time-ordered basis. Forexample, a group may include a program directed to leg pain, a programdirected to lower back pain, and a program directed to abdomen pain. Inthis manner, IMD 14 may treat different symptoms substantiallysimultaneously.

During use of IMD 14 to treat patient 12, movement of patient 12 amongdifferent posture states may affect the ability of IMD 14 to deliverconsistent efficacious therapy. For example, leads 16 may migrate towardIMD 14 when patient 12 bends over, resulting in displacement ofelectrodes and possible disruption in delivery of effective therapy. Forexample, stimulation energy transferred to target tissue may be reduceddue to electrode migration, causing reduced efficacy in terms of reliefof symptoms such as pain. As another example, leads 16 may be compressedtowards spinal cord 18 when patient 12 lies down. Such compression maycause an increase in the amount of stimulation energy transferred totarget tissue. In this case, the amplitude of stimulation therapy mayneed to be decreased to avoid causing patient 12 additional pain orunusual sensations, which may be considered undesirable side effectsthat undermine overall efficacy. Also, posture state changes may presentchanges in symptoms or symptom levels, e.g., the pain level of patient12.

Many other examples of reduced efficacy due to increased coupling ordecreased coupling of stimulation energy to target tissue, or changes insymptoms or symptom levels, may occur due to changes in posture and/oractivity level associated with patient posture state. To avoid or reducepossible disruptions in effective therapy due to posture state changes,IMD 14 may include a posture state module that detects the posture stateof patient 12 and causes the IMD 14 to automatically adjust stimulationaccording to the detected posture state. For example, a posture statemodule may include a posture state sensor such as an accelerometer thatdetects when patient 12 lies down, stands up, or otherwise changesposture.

In response to a posture state indication by the posture state module,IMD 14 may change program group, program, stimulation amplitude, pulsewidth, pulse rate, and/or one or more other parameters, groups orprograms to maintain therapeutic efficacy. When a patient lies down, forexample, IMD 14 may automatically reduce stimulation amplitude so thatpatient 12 does not need to reduce stimulation amplitude manually. Insome cases, IMD 14 may communicate with external programmer 20 topresent a proposed change in stimulation in response to a posture statechange, and receive approval or rejection of the change from a user,such as patient 12 or a clinician, before automatically applying thetherapy change.

A user, such as a clinician or patient 12, may interact with a userinterface of external programmer 20 to program IMD 14. Programming ofIMD 14 may refer generally to the generation and transfer of commands,programs, or other information to control the operation of IMD 14. Forexample, external programmer 20 may transmit programs, parameteradjustments, program selections, group selections, or other informationto control the operation of IMD 14, e.g., by wireless telemetry. As oneexample, external programmer 20 may transmit parameter adjustments tosupport therapy changes due to posture changes by patient 12. As anotherexample, a user may select programs or program groups. Again, a programmay be characterized by an electrode combination, electrode polarities,voltage or current amplitude, pulse width, pulse rate, and/or duration.A group may be characterized by multiple programs that are deliveredsimultaneously or on an interleaved or rotating basis.

In some cases, external programmer 20 may be characterized as aphysician or clinician programmer if it is primarily intended for use bya physician or clinician. In other cases, external programmer 20 may becharacterized as a patient programmer if it is primarily intended foruse by a patient. A patient programmer is generally accessible topatient 12 and, in many cases, may be a portable device that mayaccompany the patient throughout the patient's daily routine. Ingeneral, a physician or clinician programmer may support selection andgeneration of programs by a clinician for use by stimulator 14, whereasa patient programmer may support adjustment and selection of suchprograms by a patient during ordinary use.

External programmer 20 may present posture state data stored in IMD 14from the detected posture states of patient 12. The posture state datamay be acquired by external programmer 20 to generate posture stateinformation, e.g., sleep quality information, proportional postureinformation, or other information that objectively indicates how patient12 has been moving during therapy. External programmer 20 may provide auser interface to present the posture state information graphically as achart or graph, numerically, or some combination thereof. The posturestate information may be specific to a specific time interval, e.g., aday, a week, a month, or a year. In some cases, the time interval may beopen-ended in that it depends on the length of a therapy session duringwhich the posture state information is collected, which in turn isdependent on the timing of successive programming sessions in whichtherapy parameters for delivery of therapy were specified. The posturestate information may include multiple posture state determinations madeduring a time interval, such as therapy session. In some examples, theposture state information may be averaged over a time period, such as adaily average over a month time interval. The time interval may be anytime period defined by the patient, and therapy may occur over multipletime intervals. Alternatively, if the therapy session length variesaccording to the time during programming sessions, then the posturestate information may be accumulated and averaged over the entiretherapy session length.

The sleep quality information may be presented as a sleep quality chartshowing the actual or average number of transitions, or changes, betweentwo or more lying down posture states during a time interval. IMD 14 mayrecognize four different lying down posture states: lying down on thechest (lying front), lying down on the back (lying back), lying on theright side (lying right), and lying on the left side (lying left).Therefore, changes between consecutive lying down posture states may beused to detect that patient 12 is sleeping, or is attempting to sleep.Therefore, increased changes between lying down posture states mayindicate that patient 12 is restless and is not achieving deep sleep,possibly due to symptoms such as pain. The clinician or patient 12 maydesire to adjust therapy in order to better treat patient 12 when lyingdown so that the number of changes between lying down postures isreduced. In addition, the sleep quality information may quantify thenumber of times patient 12 leaves each lying down posture or moves toanother lying down posture. This information may be helpful indetermining how therapy can be improved.

The proportional posture information may be presented as a graph showingthe percentage of time patient 12 engaged in each posture state in atime interval, such as a therapy session. The percentage of time is theposture duration, and the posture duration may be calculated for asingle day, an average day within a specific time interval, or overallaverage within a specific time interval, for example. Other combinationsand averages are also contemplated as indicative of the proportion oftime patient 12 engaged in one or more posture states during a timeinterval. In addition to the posture duration, the quantified number oftimes patient 12 was engaged in the pertinent posture state during thetime interval may also be presented. A greater posture duration alongwith a fewer number of times that patient 12 has engaged in ortransitioned to or from the posture state may indicate that the therapyis relieving symptoms sufficiently to allow patient 12 to be engaged inthe posture state for a longer period of time. The proportional postureinformation may include some or all of the posture state data storedduring patient 12 therapy.

Posture state data, such as detected posture states or posture statetransitions, may be obtained over time intervals of predetermined lengthor indeterminate length. For example, IMD 14 may be configured to obtainand store posture state data over a specified time interval or one day,one week or one month. Alternatively, IMD 14 may be configured to obtainand store posture state data over an indeterminate time interval, suchas a therapy session running between successive therapy programmingsessions.

At the time a therapy session is initiated following a programmingsession, the timing of the next programming session may be unknown.Nevertheless, IMD 14 may be constructed to accumulate posture state dataover the length of the therapy session, without regard to specified timeintervals. In this case, posture information such as proportionalposture information, sleep quality information, posture changeinformation, or patient therapy adjustment information may be generatedfor the entire therapy session, e.g., as an absolute number over thetherapy session or as an average number over a portion of the therapysession, such as a day, week or month of the therapy session.

In some cases, posture state data may be simply accumulated over thecourse of a therapy session without date-stamping, time-stamping orotherwise associating the data with a particular time interval. Instead,the number of counts of a posture state, posture state transition, orpatient therapy adjustment are accumulated. In addition, the duration ofeach posture state may be tracked with another accumulator thataccumulates the length of time the patient occupies each posture state,taking into account each time that the patient initially occupies theposture state and then transitions to another posture state.

To produce posture information, IMD 14 or an external programmer 20 maythen analyze the stored posture state data over the length of theapplicable time interval, i.e., the applicable therapy session. Tocalculate an average number of patient therapy adjustments for a givenposture state over a period of time, for example, IMD 14 or programmer20 divide the number of patient therapy adjustments detected in thetherapy session by the number of applicable time periods in the therapysession.

For an average number of patient therapy adjustments for the lying backposture state per week, IMD 14 or programmer counts the number ofpatient therapy adjustments over the entire therapy session, and dividesthat count by the number of weeks in the applicable therapy session. Ifthe count was 50, and the length of the therapy session was 4.5 weeks,then the weekly average would be approximately 11.1. If the therapysession was 6.2 weeks, the weekly average would be approximately 8.1,and the monthly average (assuming 30 days per month) would beapproximately 34.6.

If this accumulation technique is used without date-stamping, it may notbe possible to generate the number of patient therapy adjustments (orother statistics) in a particular time interval, such as a particularweek or month. For example, if a therapy session is six weeks long, itmay not be possible to generate the number of average number of patienttherapy adjustments for the first week. Instead, with accumulated data,the weekly average or monthly average is obtained considering thetherapy session as a whole.

However, the use of accumulated data can significantly simplify thedesign and operation of IMD 14 or programmer 20 in storing posture statedata, patient therapy adjustment data, and other data useful inproducing posture state information. At the same time, IMD 14 orprogrammer 20 is able to provide highly useful information for a giventherapy session, so that posture state data and therapy adjustment datafor individual therapy sessions may be evaluated and compared to oneanother, e.g., to develop an efficacy trend.

IMD 14 may be constructed with a biocompatible housing, such as titaniumor stainless steel, or a polymeric material such as silicone orpolyurethane, and surgically implanted at a site in patient 12 near thepelvis. IMD 14 may also be implanted in patient 12 at a locationminimally noticeable to patient 12. Alternatively, IMD 14 may beexternal with percutaneously implanted leads. For SCS, IMD 14 may belocated in the lower abdomen, lower back, upper buttocks, or otherlocation to secure IMD 14. Leads 16 may be tunneled from IMD 14 throughtissue to reach the target tissue adjacent to spinal cord 18 forstimulation delivery.

At the distal tips of leads 16 are one or more electrodes (not shown)that transfer the electrical stimulation from each of lead 16 to thetissue of patient 12. The electrodes may be electrode pads on a paddlelead, circular (e.g., ring) electrodes surrounding the body of leads 16,conformable electrodes, cuff electrodes, segmented electrodes, or anyother type of electrodes capable of forming unipolar, bipolar ormultipolar electrode configurations for therapy. In general, ringelectrodes arranged at different axial positions at the distal ends ofleads 16 will be described for purposes of illustration.

FIG. 1B is a conceptual diagram illustrating an implantable stimulationsystem 22 including three implantable stimulation leads 16A, 16B, 16C(collectively leads 16). System 22 generally conforms to system 10 ofFIG. 1A, but includes a third lead along spinal cord 18. Accordingly,IMD 14 may deliver stimulation via combinations of electrodes carried byall three leads 16, or a subset of the three leads. The third lead,e.g., lead 16C, may include a greater number of electrodes than leads16A and 16B and be positioned between leads 16A and 16B or on one sideof either lead 16A or 16B. External programmer 20 may be initiallyinformed of the number and configuration of leads 16 in order toappropriately program stimulation therapy.

For example, leads 16A and 16B could include four electrodes, while lead16C includes eight or sixteen electrodes, thereby forming a so-called4-8-4 or 4-16-4 lead configuration. Other lead configurations, such as8-16-8, 8-4-8, 16-8-16, 16-4-16, are possible. In some cases, electrodeson lead 16C may be smaller in size and/or closer together than theelectrodes of leads 16A or 16B. Movement of lead 16C due to changingactivities or postures of patient 12 may, in some instances, moreseverely affect stimulation efficacy than movement of leads 16A or 16B.Patient 12 may further benefit from the ability of IMD 14 to detectposture states and associated changes and automatically adjuststimulation therapy to maintain therapy efficacy in a three lead system22.

FIG. 1C is a conceptual diagram illustrating an implantable drugdelivery system 24 including one delivery catheter 28 coupled to IMD 26.As shown in the example of FIG. 1C, drug delivery system 24 issubstantially similar to systems 10 and 22. However, drug deliverysystem 24 performs the similar therapy functions via delivery of drugstimulation therapy instead of electrical stimulation therapy. IMD 26functions as a drug pump in the example of FIG. 1C, and IMD 26communicates with external programmer 20 to initialize therapy or modifytherapy during operation. In addition, IMD 26 may be refillable to allowchronic drug delivery.

Although IMD 26 is shown as coupled to only one catheter 28 positionedalong spinal cord 18, additional catheters may also be coupled to IMD26. Multiple catheters may deliver drugs or other therapeutic agents tothe same anatomical location or the same tissue or organ. Alternatively,each catheter may deliver therapy to different tissues within patient 12for the purpose of treating multiple symptoms or conditions. In someembodiments, IMD 26 may be an external device which includes apercutaneous catheter that forms catheter 28 or that is coupled tocatheter 28, e.g., via a fluid coupler. In other embodiments, IMD 26 mayinclude both electrical stimulation as described in IMD 14 and drugdelivery therapy.

IMD 26 may also operate using parameters that define the method of drugdelivery. IMD 26 may include programs, or groups of programs, thatdefine different delivery methods for patient 12. For example, a programthat controls delivery of a drug or other therapeutic agent may includea titration rate or information controlling the timing of bolusdeliveries. Patient 12 may use external programmer 20 to adjust theprograms or groups of programs to regulate the therapy delivery.

Similar to IMD 14, IMD 26 may include a posture state module thatmonitors the patient 12 posture state and adjusts therapy accordingly.For example, the posture state module may indicate that patient 12transitions from lying down to standing up. IMD 26 may automaticallyincrease the rate of drug delivered to patient 12 in the standingposition if patient 12 has indicated that pain increased when standing.This automated adjustment to therapy based upon posture state may beactivated for all or only a portion of the programs used by IMD 26 todeliver therapy.

FIG. 2 is a conceptual diagram illustrating an example patientprogrammer 30 for programming stimulation therapy delivered by animplantable medical device. Patient programmer 30 is an exampleembodiment of external programmer 20 illustrated in FIGS. 1A, 1B and 1Cand may be used with either IMD 14 or IMD 26. In alternativeembodiments, patient programmer 30 may be used with an external medicaldevice. As shown in FIG. 2, patient programmer 30 provides a userinterface (not shown) for a user, such as patient 12, to manage andprogram stimulation therapy. Patient programmer 30 is protected byhousing 32, which encloses circuitry necessary for patient programmer 30to operate.

Patient programmer 30 also includes display 36, power button 38,increase button 52, decrease button 50, sync button 58, stimulation ONbutton 54, and stimulation OFF button 56. Cover 34 protects display 36from being damaged during use of patient programmer 30. Patientprogrammer 30 also includes control pad 40 which allows a user tonavigate through items displayed on display 36 in the direction ofarrows 42, 44, 46, and 48. In some embodiments, the buttons and pad 40may take the form of soft keys (e.g., with functions and contextsindicated on display 36), with functionality that may change, forexample, based on current programming operation or user preference. Inalternative embodiments, display 36 may be a touch screen in whichpatient 12 may interact directly with display 36 without the use ofcontrol pad 40 or even increase button 52 and decrease button 50.

In the illustrated embodiment, patient programmer 30 is a hand helddevice. Patient programmer 30 may accompany patient 12 throughout adaily routine. In some cases, patient programmer 30 may be used by aclinician when patient 12 visits the clinician in a hospital or clinic.In other embodiments, patient programmer 30 may be a clinicianprogrammer that remains with the clinician or in the clinic and is usedby the clinician and/or patient 12 when the patient is in the clinic. Inthe case of a clinician programmer, small size and portability may beless important. Accordingly, a clinician programmer may be sized largerthan a patient programmer, and it may provide a larger screen for morefull-featured programming.

Housing 32 may be constructed of a polymer, metal alloy, composite, orcombination material suitable to protect and contain components ofpatient programmer 30. In addition, housing 32 may be partially orcompletely sealed such that fluids, gases, or other elements may notpenetrate the housing and affect components therein. Power button 38 mayturn patient programmer 30 ON or OFF as desired by patient 12. Patient12 may control the illumination level, or backlight level, of display 36by using control pad 40 to navigate through the user interface andincrease or decrease the illumination level with decrease and increasebuttons 50 and 52. In some embodiments, illumination may be controlledby a knob that rotates clockwise and counter-clockwise to controlpatient programmer 30 operational status and display 36 illumination.Patient programmer 30 may be prevented from turning OFF during telemetrywith IMD 14 or another device to prevent the loss of transmitted data orthe stalling of normal operation. Alternatively, patient programmer 30and IMD 14 may include instructions that handle possible unplannedtelemetry interruption, such as battery failure or inadvertent deviceshutdown.

Display 36 may be a liquid crystal display (LCD), dot matrix display,organic light-emitting diode (OLED) display, touch screen, or similarmonochrome or color display capable of providing visible information topatient 12. Display 36 may provide a user interface regarding currentstimulation therapy, posture state information, provide a user interfacefor receiving feedback or medication input from patient 12, display anactive group of stimulation programs, and display operational status ofpatient programmer 30 or IMDs 14 or 26. For example, patient programmer30 may provide a scrollable list of groups, and a scrollable list ofprograms within each group, via display 36. In addition, display maypresent a visible posture state indication. Further, display 36 maypresent sleep quality information or proportional posture informationthat patient 12 may use to objectively determine therapy efficacy. Thesleep quality information or proportional posture information may bepresented graphically with shaded bars, colored features, graphicalkeys, three-dimensional graphs, embedded details, and any other elementsbeneficial to communicating the information to patient 12.

Control pad 40 allows patient 12 to navigate through items displayed ondisplay 36. Patient 12 may press control pad 40 on any of arrows 42, 44,46, and 48 in order to move to another item on display 36 or move toanother screen not currently shown on the display. In some embodiments,pressing the middle of control pad 40 may select any item highlighted indisplay 36. In other embodiments, scroll bars, a scroll wheel,individual buttons, or a joystick may perform the complete or partialfunctions of control pad 40. In alternative embodiments, control pad 40may be a touch pad that allows patient 12 to move a cursor within theuser interface displayed on display 36 to manage therapy or reviewposture state information.

Decrease button 50 and increase button 52 provide an input mechanism forpatient 12. In general, decrease button 50 may decrease the value of ahighlighted stimulation parameter every time the decrease button ispressed. In contrast, increase button 52 may increase the value of ahighlighted stimulation parameter one step every time the increasebutton is pressed. While buttons 50 and 52 may be used to control thevalue of any stimulation parameter, buttons 50 and 52 may also controlpatient feedback input. When either of buttons 50 and 52 is selected,patient programmer 30 may initiate communication with IMD 14 or 26 tochange therapy accordingly.

When depressed by patient 12, stimulation ON button 54 directsprogrammer 30 to generate a command for communication to IMD 14 thatturns on stimulation therapy. Stimulation OFF button 56 turns offstimulation therapy when depressed by patient 12. Sync button 58 forcespatient programmer 30 to communicate with IMD 14. When patient 12 entersan automatic posture response screen of the user interface, pressingsync button 58 turns on the automatic posture response to allow IMD 14to automatically change therapy according to the posture state ofpatient 12. Pressing sync button 58 again, when the automatic postureresponse screen is displayed, turns off the automatic posture response.In the example of FIG. 2, patient 12 may use control pad 40 to adjustthe volume, contrast, illumination, time, and measurement units ofpatient programmer 30.

In some embodiments, buttons 54 and 56 may be configured to performoperational functions related to stimulation therapy or the use ofpatient programmer 30. For example, buttons 54 and 56 may control thevolume of audible sounds produced by programmer 20, wherein button 54increases the volume and button 56 decreases the volume. Button 58 maybe pressed to enter an operational menu that allows patient 12 toconfigure the user interface of patient programmer 30 to the desires ofpatient 12. For example, patient 12 may be able to select a language,backlight delay time, display 36 brightness and contrast, or othersimilar options. In alternative embodiments, buttons 50 and 52 maycontrol all operational and selection functions, such as those relatedto audio volume or stimulation therapy.

Patient programmer 30 may take other shapes or sizes not describedherein. For example, patient programmer 30 may take the form of aclam-shell shape, similar to some cellular phone designs. When patientprogrammer 30 is closed, some or all elements of the user interface maybe protected within the programmer. When patient programmer 30 isopened, one side of the programmer may contain a display while the otherside may contain input mechanisms. In any shape, patient programmer 30may be capable of performing the requirements described herein.Alternative embodiments of patient programmer 30 may include other inputmechanisms such as a keypad, microphone, camera lens, or any other mediainput that allows the user to interact with the user interface providedby patient programmer 30.

In alternative embodiments, the buttons of patient programmer 30 mayperform different functions than the functions provided in FIG. 2 as anexample. In addition, other embodiments of patient programmer 30 mayinclude different button layouts or different numbers of buttons. Forexample, patient programmer 30 may even include a single touch screenthat incorporates all user interface functionality with a limited set ofbuttons or no other buttons.

FIG. 3 is a conceptual diagram illustrating an example clinicianprogrammer 60 for programming stimulation therapy delivered by animplantable medical device. Clinician programmer 60 is an exampleembodiment of external programmer 20 illustrated in FIGS. 1A, 1B and 1Cand may be used with either IMD 14 or IMD 26. In alternativeembodiments, clinician programmer 60 may be used with an externalmedical device. As shown in FIG. 3, clinician programmer 60 provides auser interface (not shown) for a user, such as a clinician, physician,technician, or nurse, to manage and program stimulation therapy. Inaddition, clinician programmer 60 may be used to review objectiveposture state information to monitor the progress and therapy efficacyof patient 12. Clinician programmer 60 is protected by housing 62, whichencloses circuitry necessary for clinician programmer 60 to operate.

Clinician programmer 60 is used by the clinician or other user to modifyand review therapy to patient 12. The clinician may define each therapyparameter value for each of the programs that define stimulationtherapy. The therapy parameters, such as amplitude, may be definedspecifically for each of the posture states that patient 12 will beengaged in during therapy. In addition, the clinician may use clinicianprogrammer 60 to define each posture state of patient 12 by using theposture cones described herein or some other technique for associatingposture state sensor output to the posture state of patient 12.

Clinician programmer 60 includes display 64 and power button 66. In theexample of FIG. 3, display 64 is a touch screen that accepts user inputvia touching certain areas within display 64. The user may use stylus 68to touch display 64 and select virtual buttons, sliders, keypads, dials,or other such representations presented by the user interface shown bydisplay 64. In some embodiments, the user may be able to touch display64 with a finger, pen, or any other pointing device. In alternativeembodiments, clinician programmer 60 may include one or more buttons,keypads, control pads, touch pads, or other devices that accept userinput, similar to patient programmer 30.

In the illustrated example, clinician programmer 60 is a hand helddevice. Clinician programmer 60 may be used within the clinic or onin-house patient calls. Clinician programmer 60 may be used tocommunicate with multiple IMDs 14 and 26 within different patients. Inthis manner, clinician programmer 60 may be capable of communicatingwith many different devices and retain patient data separate for otherpatient data. In some examples, clinician programmer 60 may be adifferent, possibly larger, device that may be less portable, such as anotebook computer, workstation, or event a remote computer thatcommunicates with IMD 14 or 26 via a remote telemetry device.

If another device such as a computer is used for processing orpresentation of programming or posture state information, it maycommunicate with a patient or clinician programmer or otherwise receiveor exchange information with a patient or clinician programmer. Forexample, posture information obtained by an IMD and uploaded to apatient or clinician programmer may be processed by the patient orclinician programmer and transmitted to another device to process theinformation for presentation to a user. As an illustration, sleepquality information may be generated based on posture state informationobtained by an IMD, e.g., by a patient or clinician programmer oranother device that receives the posture state information obtained bythe IMD.

Most, if not all, of clinician programmer 60 functions may be completedvia the touch screen of display 64. The user may program stimulationtherapy, modify programs or groups, retrieve stored therapy data,retrieve posture state information, define posture states and otheractivity information, change the contrast and backlighting of display64, or any other therapy related function. In addition, clinicianprogrammer 60 may be capable of communicating with a networked server inorder to send or receive an email or other message, retrieve programminginstructions, access a help guide, send an error message, or perform anyother function that may be beneficial to prompt therapy.

Clinician programmer 60 may also allow the clinician to objectivelymonitor posture states of patient 12. The posture and activity ofpatient 12 is stored in IMD 14 as posture state data and may bepresented by clinician programmer 60 in the form of posture stateinformation. The posture state information may be sleep qualityinformation, proportional posture information, or other information thatincludes objective data related to the frequency and duration of theposture states occupied by patient 12. This information may be presentedin an organized graphical and/or numerical manner for quick reference bythe clinician.

For example, clinician programmer 60 may be configured to display shadedgrayscale graphs of the percentage of time that patient 12 engaged ineach of the posture states. In addition, clinician programmer 60 may beconfigured to display bar charts illustrating the actual or averagenumber of posture state changes per day when patient 12 was lying downto indicate the sleep quality of patient 12. In some cases, the sleepquality information may indicate the number of transitions between eachof the posture states, e.g., the number of each of the following posturestate transitions: lying front to lying back, lying front to lyingright, lying front to lying left, lying back to lying front, lying backto lying left, lying back to lying right, lying right to lying back,lying right to lying front, lying right to lying left, lying left tolying back, lying left to lying front, or lying left to lying back.Clinician programmer 60 may also be configured to allow the clinician tointeract with the displayed graphs, charts, scatter plots, and otherinformation by selecting a portion of the information to view detailsabout that specific selected information. As an example, the clinicianmay select a bar illustrating the posture state proportions for aprevious month to view the average posture duration in time for eachposture state during that month.

Clinician programmer 60 may also allow the clinician to customize theway in which programmer 60 presents the sleep quality information andthe proportional posture information. The clinician may view sleepquality information, proportional posture information, number of patienttherapy adjustments, number of posture state transitions, or otherinformation for multiple time intervals, e.g., multiple therapysessions, simultaneously. The clinician may be able to select fromseveral types of graphs or charts, select the number of time intervalsfor which information is displayed, or even create new graphs or chartsto present only the information desired by the clinician. For example,patient 12 may have difficulty sleeping on their back due to chronicback pain. The clinician may configure clinician programmer 60 to onlyview lying back posture state information, such as the average postureduration each day and the average number of times patient 12transitioned away from one or more lying back posture states for thepast several months.

In some examples, clinician programmer 60 may not store any of theposture state data used to generate the sleep quality information andthe proportional posture information. Each time that the cliniciandesires to view the objective information related to the posture states,clinician programmer 60 may need to acquire all or some of the posturestate data from a memory of IMD 14. In other examples, clinicianprogrammer 60 may store posture state data from IMD 14 each time thatclinician programmer 60 communicates with IMD 14. In this manner,clinician programmer 60 may only need to acquire the posture state datastored in IMD 14 since the previous programming session, i.e.,communication with IMD 14. The time interval between programmingsessions may be considered a therapy session in which therapy wasdelivered according to programming performed in the previous programmingsession. Of course, clinician programmer 60 may not require all posturestate data stored during therapy. In some embodiments, only the posturestate data stored during desired time intervals, or relating to selectedposture states, may be used to present the sleep quality information orthe proportional posture information. In other embodiments, IMD 14 maysimply transfer raw data to an external programmer 20 or other computingdevice for data processing necessary to perform the tasks describedherein.

Housing 62 may be constructed of a polymer, metal alloy, composite, orcombination material suitable to protect and contain components ofclinician programmer 60. In addition, housing 62 may be partially orcompletely sealed such that fluids, gases, or other elements may notpenetrate the housing and affect components therein. Power button 66 mayturn clinician programmer 60 ON or OFF as desired by the user. Clinicianprogrammer 60 may require a password, biometric input, or other securitymeasure to be entered and accepted before the user can use clinicianprogrammer 60.

Clinician programmer 60 may take other shapes or sizes not describedherein. For example, clinician programmer 60 may take the form of aclam-shell shape, similar to some cellular phone designs. When clinicianprogrammer 60 is closed, at least a portion of display 64 is protectedwithin housing 62. When clinician programmer 60 is opened, one side ofthe programmer may contain a display while the other side may containinput mechanisms. In any shape, clinician programmer 60 may be capableof performing the requirements described herein.

FIG. 4 is a functional block diagram illustrating various components ofan IMD 14. In the example of FIG. 4, IMD 14 includes a processor 80,memory 82, stimulation generator 84, posture state module 86, telemetrycircuit 88, and power source 90. Memory 82 may store instructions forexecution by processor 80, stimulation therapy data, posture stateinformation, and any other information regarding therapy or patient 12.Therapy information may be recorded for long-term storage and retrievalby a user, and the therapy information may include any data created byor stored in IMD 14. Memory 82 may include separate memories for storinginstructions, posture state information, program histories, and anyother data that may benefit from separate physical memory modules.

Processor 80 controls stimulation generator 84 to deliver electricalstimulation via electrode combinations formed by electrodes in one ormore electrode arrays. For example, stimulation generator 84 may deliverelectrical stimulation therapy via electrodes on one or more leads 16,e.g., as stimulation pulses or continuous waveforms. Componentsdescribed as processors within IMD 14, external programmer 20 or anyother device described in this disclosure may each comprise one or moreprocessors, such as one or more microprocessors, digital signalprocessors (DSPs), application specific integrated circuits (ASICs),field programmable gate arrays (FPGAs), programmable logic circuitry, orthe like, either alone or in any suitable combination.

Stimulation generator 84 may include stimulation generation circuitry togenerate stimulation pulses or waveforms and switching circuitry toswitch the stimulation across different electrode combinations, e.g., inresponse to control by processor 80. In particular, processor 80 maycontrol the switching circuitry on a selective basis to causestimulation generator 84 to deliver electrical stimulation to selectedelectrode combinations and to shift the electrical stimulation todifferent electrode combinations in a first direction or a seconddirection when the therapy must be delivered to a different locationwithin patient 12. In other embodiments, stimulation generator 84 mayinclude multiple current sources to drive more than one electrodecombination at one time. In this case, stimulation generator 84 maydecrease current to the first electrode combination and simultaneouslyincrease current to the second electrode combination to shift thestimulation therapy.

An electrode configuration, e.g., electrode combination and associatedelectrode polarities, may be represented by a data stored in a memorylocation, e.g., in memory 82, of IMD 14. Processor 80 may access thememory location to determine the electrode combination and controlstimulation generator 84 to deliver electrical stimulation via theindicated electrode combination. To change electrode configurations,amplitudes, pulse rates, or pulse widths, processor 80 may commandstimulation generator 84 to make the appropriate changed to therapyaccording to instructions within memory 82 and rewrite the memorylocation to indicate the changed therapy. In other embodiments, ratherthan rewriting a single memory location, processor 80 may make use oftwo or more memory locations.

When activating stimulation, processor 80 may access not only the memorylocation specifying the electrode combination but also other memorylocations specifying various stimulation parameters such as voltage orcurrent amplitude, pulse width and pulse rate. Stimulation generator 84,e.g., under control of processor 80, then makes use of the electrodecombination and parameters in formulating and delivering the electricalstimulation to patient 12. Processor 80 also may control telemetrycircuit 88 to send and receive information to and from externalprogrammer 20. For example, telemetry circuit 88 may send information toand receive information from patient programmer 30. An exemplary rangeof electrical stimulation parameters likely to be effective in treatingchronic pain, e.g., when applied to spinal cord 18, are listed below.While stimulation pulses are described, stimulation signals may be ofany of a variety of forms such as sine waves or the like.

1. Pulse Rate: between approximately 0.5 Hz and 1200 Hz, more preferablybetween approximately 5 Hz and 250 Hz, and still more preferably betweenapproximately 30 Hz and 130 Hz.

2. Amplitude: between approximately 0.1 volts and 50 volts, morepreferably between approximately 0.5 volts and 20 volts, and still morepreferably between approximately 1 volt and 10 volts. In otherembodiments, a current amplitude may be defined as the biological loadin the voltage that is delivered. For example, the range of currentamplitude may be between 0.1 milliamps (mA) and 50 mA.

3. Pulse Width: between about 10 microseconds and 5000 microseconds,more preferably between approximately 100 microseconds and 1000microseconds, and still more preferably between approximately 180microseconds and 450 microseconds.

In other applications, different ranges of parameter values may be used.For deep brain stimulation (DBS), as one example, alleviation orreduction of symptoms associated with Parkinson's disease, essentialtremor, epilepsy or other disorders may make use of stimulation having apulse rate in the range of approximately 0.5 to 1200 Hz, more preferably5 to 250 Hz, and still more preferably 30 to 185 Hz, and a pulse widthin the range of approximately 10 microseconds and 5000 microseconds,more preferably between approximately 60 microseconds and 1000microseconds, still more preferably between approximately 60microseconds and 450 microseconds, and even more preferably betweenapproximately 60 microseconds and 150 microseconds. Amplitude rangessuch as those described above with reference to SCS, or other amplituderanges, may be used for different DBS applications.

Processor 80 stores stimulation parameters in memory 82, e.g., asprograms and groups of programs. Upon selection of a particular programgroup, processor 80 may control stimulation generator 84 to deliverstimulation according to the programs in the groups, e.g.,simultaneously or on a time-interleaved basis. A group may include asingle program or multiple programs. As mentioned previously, eachprogram may specify a set of stimulation parameters, such as amplitude,pulse width and pulse rate. In addition, each program may specify aparticular electrode combination for delivery of stimulation. Again, theelectrode combination may specify particular electrodes in a singlearray or multiple arrays, e.g., on a single lead or among multipleleads.

Posture state module 86 allows IMD 14 to sense the patient posturestate, e.g., posture, activity or any other static position or motion ofpatient 12. In the example of FIG. 4, posture state module 86 mayinclude one or more posture state sensors, e.g., one or moreaccelerometers such as three-axis accelerometers, capable of detectingstatic orientation or vectors in three-dimensions. The three-axisaccelerometer may be a micro-electro-mechanical accelerometer. In otherexamples, posture state module 86 may alternatively or additionallyinclude one or more gyroscopes, pressure transducers or other sensors tosense the posture state of patient 12. Posture state informationgenerated by posture state module 86 and processor 80 may correspond toan activity, posture, or posture and activity undertaken by patient 12or a gross level of physical activity, e.g., activity counts based onfootfalls or the like.

Posture state information from posture state module 86 may be stored inmemory 82 to be later reviewed by a clinician, used to adjust therapy,presented as a posture state indication to patient 12, or somecombination thereof. As an example, processor 80 may record the posturestate parameter value, or output, of the 3-axis accelerometer and assignthe posture state parameter value to a certain predefined postureindicated by the posture state parameter value. In this manner, IMD 14may be able to track how often patient 12 remains within a certainposture defined within memory 82. IMD 14 may also store which group orprogram was being used to deliver therapy when patient 12 was in thesensed posture. Further, processor 80 may also adjust therapy for a newposture when posture state module 86 indicates that patient 12 has infact changed postures. Therefore, IMD 14 may be configured to provideposture responsive stimulation therapy to patient 12. Stimulationadjustments in response to posture state may be automatic orsemi-automatic (subject to patient approval). In many cases, fullyautomatic adjustments may be desirable so that IMD 14 may react morequickly to posture state changes.

As described herein, the posture state data, or raw data of the posturestate information, is stored by system 10 to be used at a later time togenerate sleep quality information and proportional posture information,which may be referred to generally as posture state output for apatient. Memory 82 may store all of the posture state data detectedduring therapy or use of IMD 14, or memory 82 may periodically offloadthe posture state data to clinician programmer 60 or a differentexternal programmer 20 or device. In other examples, memory 82 mayreserve a portion of the memory to store recent posture state dataeasily accessible to processor 80 for analysis. In addition, olderposture state data may be compressed within memory 82 to require lessmemory storage until later needed by external programmer 20 or processor80.

A posture state parameter value provided from posture state module 86that indicates the posture state of patient 12 may constantly varythroughout the daily activities of patient 12. However, a certainactivity (e.g., walking, running, or biking) or a posture (e.g.,standing, sitting, or lying down) may include multiple posture stateparameter values from posture state module 86. In this manner, a posturestate may include a broad range of posture state parameter values.Memory 82 may include definitions for each posture state of patient 12.In one example, the definitions of each posture state may be illustratedas a cone in three-dimensional space. Whenever the posture stateparameter value, e.g., a vector, from the three-axis accelerometer ofposture state module 86 resides within a predefined cone, processor 80indicates that patient 12 is in the posture state of the cone. In otherexamples, posture state parameter value from the 3-axis accelerometermay be compared to a look-up table or equation to determine the posturestate in which patient 12 currently resides.

Posture responsive stimulation may allow IMD 14 to implement a certainlevel of automation in therapy adjustments. Automatically adjustingstimulation may free patient 12 from the constant task of manuallyadjusting therapy parameters each time patient 12 changes posture orstarts and stops a certain posture state. Such manual adjustment ofstimulation parameters can be tedious, requiring patient 12 to, forexample, depress one or more keys of patient programmer 30 multipletimes during the patient posture state to maintain adequate symptomcontrol. Alternatively, patient 12 may be unable to manually adjust thetherapy if patient programmer 30 is unavailable or patient 12 ispreoccupied. In some embodiments, patient 12 may eventually be able toenjoy posture state responsive stimulation therapy without the need tocontinue making changes for different postures via patient programmer30. Instead, patient 12 may transition immediately or over time to fullyautomatic adjustments based on posture state.

Although posture state module 86 is described as containing the 3-axisaccelerometer, posture state module 86 may contain multiple single-axisaccelerometers, dual-axis accelerometers, 3-axis accelerometers, or somecombination thereof. In some examples, an accelerometer or other sensormay be located within or on IMD 14, on one of leads 16 (e.g., at thedistal tip or at an intermediate position), an additional sensor leadpositioned somewhere within patient 12, within an independentimplantable sensor, or even worn on patient 12. For example, one or moremicrosensors may be implanted within patient 12 to communicate posturestate information wirelessly to IMD 14. In this manner, the patient 12posture state may be determined from multiple posture state sensorsplaced at various locations on or within the body of patient 12.

In some embodiments, processor 80 processes the analog output of theposture state sensor in posture state module 86 to determine activityand/or posture data. For example, where the posture state sensorcomprises an accelerometer, processor 80 or a processor of posture statemodule 86 may process the raw signals provided by the posture statesensor to determine activity counts. In some embodiments, processor 80may process the signals provided by the posture state sensor todetermine velocity of motion information along each axis.

In one example, each of the x, y, and z signals provided by the posturestate sensor has both a DC component and an AC component. The DCcomponents describes the gravitational force exerted upon the sensor andcan thereby be used to determine orientation of the sensor within thegravitational field of the earth. Assuming the orientation of the sensoris relatively fixed with respect to the patient, the DC components ofthe x, y and z signals may be utilized to determine the patient'sorientation within the gravitational field, and hence to determine theposture of the patient.

The AC component of the x, y and z signals yields information aboutpatient motion. In particular, the AC component of a signal may be usedto derive a value for an activity describing the patient's motion oractivity. This activity may involve a level, direction of motion, oracceleration of the patient.

One method for determining the activity is an activity count. Anactivity count may be used to indicate the activity or activity level ofpatient 12. For example, a signal processor may sum the magnitudes ofthe AC portion of an accelerometer signal for N consecutive samples. Forinstance, assuming sampling occurs as 25 Hz, N may be set to 25, so thatcount logic provides the sum of the samples that are obtained in onesecond. This sum may be referred to as an “activity count”. The number“N” of consecutive samples may be selected by the processor based on thecurrent posture state, if desired. The activity count may be theactivity portion of the activity parameter value that is added to theposture portion. The resulting activity parameter value may thenincorporate both activity and posture to generate an accurate indicationof the motion of patient 12.

As another example, the activity parameter value may be defineddescribing direction of motion. This activity parameter value may beassociated with a vector and an associated tolerance, which may be adistance from the vector. Another example of an activity parameter valuerelates to acceleration. The value quantifying a level of change ofmotion over time in a particular direction may be associated with thisparameter referenced in the activity parameter value.

In other embodiments, posture state module 86 may additionally oralternatively be configured to sense one or more physiologicalparameters of patient 12. For example, physiological parameters mayinclude heart rate, electromyography (EMG), an electroencephalogram(EEG), an electrocardiogram (ECG), temperature, respiration rate, or pH.These physiological parameters may be used by processor 80, in someembodiments, to confirm or reject changes in sensed posture state thatmay result from vibration, patient travel (e.g., in an aircraft, car ortrain), or some other false positive of posture state.

Wireless telemetry in IMD 14 with external programmer 20, e.g., patientprogrammer 30 or clinician programmer 60, or another device may beaccomplished by radio frequency (RF) communication or proximal inductiveinteraction of IMD 14 with external programmer 20. Telemetry circuit 88may send information to and receive information from external programmer20 on a continuous basis, at periodic intervals, at non-periodicintervals, or upon request from the stimulator or programmer. To supportRF communication, telemetry circuit 88 may include appropriateelectronic components, such as amplifiers, filters, mixers, encoders,decoders, and the like.

Power source 90 delivers operating power to the components of IMD 14.Power source 90 may include a small rechargeable or non-rechargeablebattery and a power generation circuit to produce the operating power.Recharging may be accomplished through proximal inductive interactionbetween an external charger and an inductive charging coil within IMD14. In some embodiments, power requirements may be small enough to allowIMD 14 to utilize patient motion and implement a kineticenergy-scavenging device to trickle charge a rechargeable battery. Inother embodiments, traditional batteries may be used for a limitedperiod of time. As a further alternative, an external inductive powersupply could transcutaneously power IMD 14 when needed or desired.

FIG. 5 is a functional block diagram illustrating various components ofan IMD 26 that is a drug pump. IMD 26 is a drug pump that operatessubstantially similar to IMD 14 of FIG. 4. IMD 26 includes processor 92,memory 94, pump module 96, posture state module 98, telemetry circuit100, and power source 102. Instead of stimulation generator 84 of IMD14, IMD 26 includes pump module 96 for delivering drugs or some othertherapeutic agent via catheter 28. Pump module 96 may include areservoir to hold the drug and a pump mechanism to force drug out ofcatheter 28 and into patient 12.

Processor 92 may control pump module 96 according to therapyinstructions stored within memory 94. For example, memory 94 may containthe programs or groups of programs that define the drug delivery therapyfor patient 12. A program may indicate the bolus size or flow rate ofthe drug, and processor 92 may accordingly deliver therapy. Processor 92may also use posture state information from posture state module 98 toadjust drug delivery therapy when patient 12 changes posture states,e.g., adjusts his or her posture. In alternative embodiments, system 10may be employed by an implantable medical device that delivers therapyvia both electrical stimulation therapy and drug delivery therapy as acombination of IMD 14 and IMD 26.

FIG. 6 is a functional block diagram illustrating various components ofan external programmer 20 for IMDs 14 or 26. As shown in FIG. 6,external programmer 20 includes processor 104, memory 108, telemetrycircuit 110, user interface 106, and power source 112. Externalprogrammer 20 may be embodied as patient programmer 30 or clinicianprogrammer 60. A clinician or patient 12 interacts with user interface106 in order to manually change the stimulation parameters of a program,change programs within a group, turn posture responsive stimulation ONor OFF, view therapy information, view posture state information, orotherwise communicate with IMDs 14 or 26.

User interface 106 may include a screen and one or more input buttons,as in the example of patient programmer 30, that allow externalprogrammer 20 to receive input from a user. Alternatively, userinterface 106 may additionally or only utilize a touch screen display,as in the example of clinician programmer 60. The screen may be a liquidcrystal display (LCD), dot matrix display, organic light-emitting diode(OLED) display, touch screen, or any other device capable of deliveringand/or accepting information.

Input buttons for user interface 106 may include a touch pad, increaseand decrease buttons, emergency shut off button, and other buttonsneeded to control the stimulation therapy, as described above withregard to patient programmer 30. Processor 104 controls user interface106, retrieves data from memory 108 and stores data within memory 108.Processor 104 also controls the transmission of data through telemetrycircuit 110 to IMDs 14 or 26. Memory 108 includes operation instructionsfor processor 104 and data related to patient 12 therapy.

User interface 106 is configured to present sleep quality informationand proportional posture information to the user. In addition topresenting text, user interface 106 may be configured to presentgraphical representations to the user in grayscale, color, and othervisual formats. For example, user interface 106 may be configured topresent the proportional posture information as a graphical postureduration graph that visually indicates the proportion of time patient 12has been engaged in each posture state. User interface 106 may be ableto reconfigure the displayed posture duration graph to show proportionalposture information throughout different time intervals of the therapy,such as over days, weeks, months, or years. In particular, theproportional posture information can be shown for multiple timeintervals simultaneously, permitting a clinician to observe a trend inthe information. The time intervals may also be defined by the dateswhen the patient visited with a clinician for a clinic programmingsession or received program parameters via a remote programming session.In this manner, in some examples, the time interval may be referred toas an intersession time interval or a therapy session, i.e., a therapysession between programming sessions. The user may also interact withuser interface 106 to present comparison posture duration graphs thatindicate the difference in patient 12 posture during two or morespecific time intervals. From this information, the user may be able todetermine trends in the therapy and adjust the therapy parametersaccordingly in order to achieve effective therapy.

The sleep quality information, proportional posture information, andother information related to the posture states, i.e., posture stateinformation, may be stored within memory 108 or within another datastorage device, such as a hard drive, flash memory or the like. Externalprogrammer 20 may store information obtained from previouslyinterrogating IMD 14 so that that same information does not need to beretrieved from the IMD repeatedly, and so that IMD 14 may overwriteinformation, if necessary, in some implementations. Hence, externalprogrammer 20 may retrieve new information from IMD 14, i.e.,information that has been newly obtained since the previousinterrogation, and also rely on archived information stored in theprogrammer or elsewhere. External programmer 20 may store the posturestate information in memory 108 during communication sessions with IMD14. The user may then have quick access to the posture state informationwithout first communicating to IMD 14 and acquiring the posture stateinformation from IMD 14 every time that the user desired to review thesleep quality information or proportional posture information, forexample. If memory 108 does store posture state information from patient12, memory 108 may use one or more hardware or software securitymeasures to protect the identify of patient 12. For example, memory 108may have separate physical memories for each patient or the user may berequired to enter a password to access each patient's posture statedata.

Telemetry circuit 110 allows the transfer of data to and from IMD 14, orIMD 26. Telemetry circuit 110 may communicate automatically with IMD 14at a scheduled time or when the telemetry circuit detects the proximityof the stimulator. Alternatively, telemetry circuit 110 may communicatewith IMD 14 when signaled by a user through user interface 106. Tosupport RF communication, telemetry circuit 110 may include appropriateelectronic components, such as amplifiers, filters, mixers, encoders,decoders, and the like. Power source 112 may be a rechargeable battery,such as a lithium ion or nickel metal hydride battery. Otherrechargeable or conventional batteries may also be used. In some cases,external programmer 20 may be used when coupled to an alternatingcurrent (AC) outlet, i.e., AC line power, either directly or via anAC/DC adapter.

In some examples, external programmer 20 may be configured to rechargeIMD 14 in addition to programming IMD 14. In this case, the programmermay be integrated with recharging components in a common device.Alternatively, a recharging device may be capable of communication withIMD 14. Then, the recharging device may be able to transfer programminginformation, data, or any other information described herein to IMD 14.In this manner, the recharging device may be able to act as anintermediary communication device between external programmer 20 and IMD14. The techniques described herein may be communicated between IMD 14via any type of external device capable of communication with IMD 14.

FIG. 7 is a block diagram illustrating an example system 120 thatincludes an external device, such as a server 122, and one or morecomputing devices 124A-124N, that are coupled to IMD 14 and externalprogrammer 20 shown in FIGS. 1A-1C via a network 126. In this example,IMD 14 may use its telemetry circuit 88 to communicate with externalprogrammer 20 via a first wireless connection, and to communication withan access point 128 via a second wireless connection. In other examples,IMD 26 may also be used in place of IMD 14, and external programmer 20may be either patient programmer 30 or clinician programmer 60.

In the example of FIG. 7, access point 128, external programmer 20,server 122, and computing devices 124A-124N are interconnected, and ableto communicate with each other, through network 126. In some cases, oneor more of access point 128, external programmer 20, server 122, andcomputing devices 124A-124N may be coupled to network 126 through one ormore wireless connections. IMD 14, external programmer 20, server 122,and computing devices 124A-124N may each comprise one or moreprocessors, such as one or more microprocessors, digital signalprocessors (DSPs), application specific integrated circuits (ASICs),field programmable gate arrays (FPGAs), programmable logic circuitry, orthe like, that may perform various functions and operations, such asthose described in this disclosure.

Access point 128 may comprise a device, such as a home monitoringdevice, that connects to network 126 via any of a variety ofconnections, such as telephone dial-up, digital subscriber line (DSL),or cable modem connections. In other embodiments, access point 128 maybe coupled to network 126 through different forms of connections,including wired or wireless connections.

During operation, IMD 14 may collect and store various forms of data.For example, IMD 14 may collect sensed posture state information duringtherapy that indicate how patient 12 moves throughout each day. In somecases, IMD 14 may directly analyze the collected data to evaluate theposture state of patient 12, such as what percentage of time patient 12was in each identified posture. In other cases, however, IMD 14 may sendstored data relating to posture state information to external programmer20 and/or server 122, either wirelessly or via access point 128 andnetwork 126, for remote processing and analysis. For example, IMD 14 maysense, process, trend and evaluate the sensed posture state information.Alternatively, processing, trending and evaluation functions may bedistributed to other devices such as external programmer 20 or server122, which are coupled to network 126. In addition, posture stateinformation may be archived by any of such devices, e.g., for laterretrieval and analysis by a clinician.

In some cases, IMD 14, external programmer 20 or server 122 may processposture state information or raw data and/or therapy information intoposture state output such as a displayable posture state report, whichmay be displayed via external programmer 20 or one of computing devices124A-124N. The posture state report may contain trend data forevaluation by a clinician, e.g., by visual inspection of graphic data.In some cases, the posture state report may include the number ofactivities patient 12 conducted, a percentage of time patient 12 was ineach posture state, the average time patient 12 was continuously withina posture state, what group or program was being used to deliver therapyduring each activity, the number of patient adjustments to therapyduring each respective posture state, or any other information relevantto patient 12 therapy over one or more time intervals, such as one ormore therapy sessions, based on analysis and evaluation performedautomatically by IMD 14, external programmer 20 or server 122. Aclinician or other trained professional may review and/or annotate theposture state report, and possibly identify any problems or issues withthe therapy that should be addressed.

In the manner of FIG. 7, a clinician, physician, technician, or evenpatient 12, may review objectivity data with respect to the posturestates of patient 12. The objectivity data may be sleep qualityinformation or proportional posture information that indicates howpatient 12 has been moving during the symptom diagnosis or deliveredtherapy, or posture transition information or patient therapy adjustmentinformation that indicates the number of posture transitions and numberof patient therapy adjustments for each posture state, respectively. Theuser may remotely monitor the progress and trends of patient 12 over thecourse of a therapy sessions or over multiple therapy sessions, limitingthe number of times that patient 12 may need to physically visit theclinician. This monitoring may also reduce the time needed to findefficacious therapy parameters by allowing the clinician to morefrequently monitor sleep quality information and proportional postureinformation. Any of the user interfaces described herein with respect topatient programmer 30 or clinician programmer 60 may also be presentedvia any of computing devices 124A-124N.

In some cases, server 122 may be configured to provide a secure storagesite for archival of posture state information that has been collectedfrom IMD 14 and/or external programmer 20. Network 126 may comprise alocal area network, wide area network, or global network, such as theInternet. In some cases, external programmer 20 or server 122 mayassemble posture state information in web pages or other documents forviewing by trained professionals, such as clinicians, via viewingterminals associated with computing devices 124A-124N. System 120 may beimplemented, in some aspects, with general network technology andfunctionality similar to that provided by the Medtronic CareLink®Network developed by Medtronic, Inc., of Minneapolis, Minn.

Although some examples of the disclosure may involve posture stateinformation and data, system 120 may be employed to distribute anyinformation relating to the treatment of patient 12 and the operation ofany device associated therewith. For example, system 120 may allowtherapy errors or device errors to be immediately reported to theclinician. In addition, system 120 may allow the clinician to remotelyintervene in the therapy and reprogram IMD 14, patient programmer 30, orcommunicate with patient 12. In an additional example, the clinician mayutilize system 120 to monitor multiple patients and share data withother clinicians in an effort to coordinate rapid evolution of effectivetreatment of patients. Further, posture state detection may also be usedto provide notifications, such as providing notification via a wirelesslink to a care giver that a patient has potentially experienced a fall.

Furthermore, although the disclosure is described with respect to SCStherapy, such techniques may be applicable to IMDs that convey othertherapies in which posture state information is important, such as,e.g., DBS, pelvic floor stimulation, gastric stimulation, occipitalstimulation, functional electrical stimulation, and the like. Also, insome aspects, techniques for evaluating posture state information, asdescribed in this disclosure, may be applied to IMDs that are generallydedicated to sensing or monitoring and do not include stimulation orother therapy components. For example, an implantable monitoring devicemay be implanted in conjunction with an implantable stimulation device,and be configured to evaluate sensing integrity of leads or electrodesassociated with the implantable monitoring device based on sensedsignals evoked by delivery of stimulation by the implantable stimulationdevice.

FIGS. 8A-8C are conceptual illustrations of posture state spaces 140,152, 155 within which posture state reference data may define theposture state of patient 12. Posture state reference data may definecertain regions associated with particular posture states of patient 12within the respective posture state spaces 140, 152, 155. The output ofone or more posture state sensors may be analyzed by posture statemodule 86 with respect to posture state spaces 140, 152, 155 todetermine the posture state of patient 12. For example, if the output ofone or more posture state sensors is within a particular posture regiondefined by posture state reference data, posture state module 86 maydetermine that patient 12 is within the posture state associated withthe respective posture state region.

In some cases, one or more posture state regions may be defined asposture state cones. Posture state cones may be used to define a posturestate of patient 12 based on the output from a posture state sensor of aposture state according to an example method for posture statedetection. A posture state cone may be centered about a posture statereference coordinate vector that corresponds to a particular posturestate. In the examples of FIGS. 8A and 8B, the posture state module 86of IMD 14 or IMD 26 may use a posture state sensor, e.g., a three-axisaccelerometer that provides data indicating the posture state of patient12, to sense posture vectors. While the sensed data may be indicative ofany posture state, postures of patient 12 will generally be used belowto illustrate the concept of posture cones. As shown in FIG. 8A, posturestate space 140 represents a vertical plane dividing patient 12 fromleft and right sides, or the sagittal plane. A posture state parametervalue from two axes of the posture state sensor may be used to determinethe current posture state of patient 12 according to the posture statespace 140. The posture state data may include x, y and z coordinatevalues.

A posture cone may be defined by a reference coordinate vector for agiven posture state in combination with a distance or angle defining arange of coordinate vectors within a cone surrounding the posturereference coordinate vector. Alternatively, a posture cone may bedefined by a reference coordinate vector and a range of cosine valuescomputed using the reference coordinate vector as an adjacent vector andany of the outermost vectors of the cone as a hypotenuse vector. If asensed posture state vector is within an applicable angle or distance ofthe reference coordinate vector, or if the sensed posture state vectorand the reference coordinate vector produce a cosine value in aspecified cosine range, then posture state vector is determined toreside within the posture cone defined by the reference coordinatevector.

Posture state space 140 is segmented into different posture cones thatare indicative of a certain posture state of patient 12. In the exampleof FIG. 8A, upright cone 142 indicates that patient 12 is sitting orstanding upright, lying back cone 148 indicates that patient 12 is lyingback down, lying front cone 144 indicates that patient 12 is lying chestdown, and inverted cone 146 indicates that patient 12 is in an invertedposition. Other cones may be provided, e.g., to indicate that patient 12is lying on the right side or left side. For example, a lying rightposture cone and a lying left posture cone may be positioned outside ofthe sagittal plane illustrated in FIG. 8A. In particular, the lyingright and lying left posture cones may be positioned in a coronal planesubstantially perpendicular to the sagittal plane illustrated in FIG.8A. For ease of illustration, lying right and lying left cones are notshown in FIG. 8A.

Vertical axis 141 and horizontal axis 143 are provided for orientationof posture state area 140, and are shown as orthogonal for purposes ofillustration. However, posture cones may have respective posturereference coordinate vectors that are not orthogonal in some cases. Forexample, individual reference coordinate vectors for cones 142 and 146may not share the same axis, and reference coordinate vectors for cones144 and 148 may not share the same axis. Also, reference coordinatevectors for cones 144 and 148 may or may not be orthogonal to referencecoordinates vectors for cones 142, 146. Moreover, the referencecoordinate vectors need not reside in the same plane. Therefore,although orthogonal axes are shown in FIG. 8A for purposes ofillustration, respective posture cones may be defined by individualizedreference coordinate vectors for the cones.

IMD 14 may monitor the posture state parameter value of the posturestate sensor to produce a sensed coordinate vector and identify thecurrent posture of patient 12 by identifying which cone the sensedcoordinated vector of the posture state sensor module 86 resides. Forexample, if the posture state parameter value corresponds to a sensedcoordinate vector that falls within lying front cone 144, IMD 14determines that patient 12 is lying down on their chest. IMD 14 maystore this posture information as a determined posture state or as rawoutput from the posture state sensor, change therapy according to theposture, or both. Additionally, IMD 14 may communicate the postureinformation to patient programmer 30 so that the patient programmer canpresent a posture state indication to patient 12.

In addition, posture state area 140 may include hysteresis zones 150A,150B, 150C, and 150D (collectively “hysteresis zones 150”). Hysteresiszones 150 are positions within posture state area 140 where no posturecones have been defined. Hysteresis zones 150 may be particularly usefulwhen IMD 14 utilizes the posture state information and posture cones toadjust therapy automatically. If the posture state sensor indicates thatpatient 12 is in upright cone 142, IMD 14 would not detect that patient12 has entered a new posture cone until the posture state parametervalue indicates a different posture cone. For example, if IMD 14determines that patient 12 moves to within hysteresis zone 150A fromupright cone 142, IMD 14 retains the posture as upright. In this manner,IMD 14 does not change the corresponding therapy until patient 12 fullyenters a different posture cone. Hysteresis zones 150 prevent IMD 14from continually oscillating between different therapies when patient12's posture state resides near a posture cone boundary.

Each posture cone 142, 144, 146, 148 may be defined by an angle inrelation to a reference coordinate vector defined for the respectiveposture cone. Alternatively, some posture cones may be defined by anangle relative to a reference coordinate vector for another posturecone. For example, lying postures may be defined by an angle withrespect to a reference coordinate vector for an upright posture cone. Ineach case, as described in further detail below, each posture cone maybe defined by an angle in relation to a reference coordinate posturevector defined for a particular posture state. The reference coordinatevector may be defined based on posture sensor data generated by aposture state sensor while patient 12 occupies a particular posturestate desired to be defined using the reference coordinate vector. Forexample, a patient may be asked to occupy a posture so that a referencecoordinate vector can be sensed for the respective posture. In thismanner, vertical axis 141 may be specified according to the patient'sactual orientation. Then, a posture cone can be defined using thereference coordinate vector as the center of the cone.

Vertical axis 141 in FIG. 8A may correspond to a reference coordinatevector sensed while the patient was occupying an upright posture state.Similarly, a horizontal axis 143 may correspond to a referencecoordinate vector sensed while the patient is occupying a lying posturestate. A posture cone may be defined with respect to the referencecoordinate vector. Although a single axis is shown extending through theupright and inverted cones 142, 146, and another single axis is shownextending through the lying up (back) and lying down (front) cones 144,148, individual reference coordinate vectors may be used for respectivecones, and the reference coordinate vectors may not share the same axes,depending on differences between the reference coordinate vectorsobtained for the posture cones.

Posture cones may be defined by the same angle or different angles,symmetrical to either axis, or asymmetrical to either axis. For example,upright cone 142 may have an angle of eighty degrees, +40 degrees to −40degrees from the positive vertical axis 141. In some cases, lying conesmay be defined relative to the reference coordinate vector of theupright cone 142. For example, lying down cone 148 may have an angle ofeighty degrees, −50 degrees to −130 degrees from the positive verticalaxis 141. Inverted cone 146 may have an angle of eighty degrees, −140degrees to +140 degrees from vertical axis 141. In addition, lying downcone 144 may have an angle of eighty degrees, +50 degrees to +130degrees from the positive vertical axis 141. In other examples, eachposture cone may have varying angle definitions, and the angles maychange during therapy delivery to achieve the most effective therapy forpatient 12.

Alternatively or additionally, instead of an angle, posture cones 144,146, 148, 148 may be defined by a cosine value or range of cosine valuesin relation to vertical axis 141, horizontal axis 143, or some otheraxis, such as, e.g., individual reference coordinate vectors for therespective cones. For example, a posture cone may be defined by a cosinevalue that defines the minimum cosine value, calculated using areference coordinate vector and a respective coordinate vector sensed bya posture state sensor at any point in time. In the cosine computation,the value (adjacent/hypotenuse) can be computed using the magnitude ofthe coordinate reference vector as the adjacent and a vector at theoutermost extent of the cone as the hypotenuse to define a range ofcosine values consistent with the outer bound of the cone.

For upright cone 142, the cosine range may extend from the maximumcosine value of 1.0, corresponding to a sensed vector that matches thereference coordinate vector of the upright cone, to a minimum cosinevalue that corresponds to a sensed vector at the outer limit of theupright cone. As another example, for lying cone 144, the cosine rangemay extend from the maximum cosine value of 1.0, corresponding to asensed vector that matches the reference coordinate vector of the lyingcone, to a minimum cosine value that corresponds to a sensed vector atthe outer limit of the lying cone. Alternatively, the lying cone 144 maybe defined with reference to the upright cone 142, such that the cosinerange may extend between a maximum and minimum values determinedrelative to the reference coordinate vector for the upright cone.

In other examples, posture state area 140 may include additional posturecones than those shown in FIG. 8A. For example, a reclining cone may belocated between upright cone 142 and lying back cone 148 to indicatewhen patient 12 is reclining back (e.g., in a dorsal direction). In thisposition, patient 12 may need a different therapy to effectively treatsymptoms. Different therapy programs may provide efficacious therapy topatient 12 when patient 12 is in each of an upright posture (e.g.,within upright cone 142), lying back posture (e.g., within lying backcone 148), and a reclining back posture. Thus, a posture cone thatdefines the reclining back posture may be useful for providingefficacious posture-responsive therapy to patient 12. In other examples,posture state area 140 may include fewer posture cones than cones 142,144, 146, 148 shown in FIG. 8A. For example, inverted cone 146 may bereplaced by a larger lying back cone 148 and lying front cone 144.

FIG. 8B illustrates an example posture state space 152 that is athree-dimensional space in which the posture state parameter value fromthe posture state sensor is placed in relation to the posture cones.Posture state space 152 is substantially similar to posture state area140 of FIG. 8A. However, the posture state parameter value derived fromall three axes of a 3-axis accelerometer may be used to accuratelydetermine the posture state of patient 12. In the example of FIG. 8B,posture state space 152 includes upright cone 154, lying back cone 156,and lying front cone 158. Posture state space 152 also includeshysteresis zones (not shown) similar to those of posture state area 140.In the example of FIG. 8B, the hysteresis zones are the spaces notoccupied by a posture cone, e.g., upright cone 154, lying back cone 156,and lying front cone 158.

Posture cones 154, 156 and 158 also are defined by a respective centerline 153A, 153B, or 153C, and associated cone angle A, B or C. Forexample, upright cone 154 is defined by center line 153A that runsthrough the center of upright cone 154. Center line 153A may correspondto an axis of the posture state sensor or some other calibrated vector.In some embodiments, each center line 153A, 153B, 153C may correspond toa posture reference coordinate vectors defined for the respectivepostures, e.g., the upright posture. For instance, assuming that patient12 is standing, the DC portion of the x, y, and z signals detected bythe posture state sensor of posture state module 86 define a posturevector that corresponds to center line 153A. The x, y, and z signals maybe measured while patient 12 is known to be in a specified position,e.g., standing, and the measured vector may be correlated with theupright posture state. Thereafter, when the DC portions of the posturestate sensor signal are within some predetermined cone tolerance orproximity, e.g., as defined by an angle, distance or cosine value, ofthe posture reference coordinate vector (i.e., center line 153A), it maybe determined that patient 12 is in the upright posture. In this manner,a sensed posture coordinate vector may be initially measured based onthe output of one or more posture state sensors of posture state module86, associated with a posture state, such as upright, as a referencecoordinate vector, and then later used to detect a patient's posturestate.

As previously indicated, it may be desirable to allow some tolerance tobe associated with a defined posture state, thereby defining a posturecone or other volume. For instance, in regard to the upright posturestate, it may be desirable to determine that a patient who is uprightbut leaning slightly is still in the same upright posture state. Thus,the definition of a posture state may generally include not only aposture reference coordinate vector (e.g., center line 153A), but also aspecified tolerance. One way to specify a tolerance is by providing anangle, such as cone angle A, relative to coordinate reference vector153A, which results in posture cone 154 as described herein. Cone angleA is the deflection angle, or radius, of upright cone 154. The totalangle that each posture cone spans is double the cone angle. The coneangles A, B, and C may be generally between approximately 1 degree andapproximately 70 degrees. In other examples, cone angles A, B, and C maybe between approximately 10 degrees and 30 degrees. In the example ofFIG. 8B, cone angles A, B, and C are approximately 20 degrees. Coneangles A, B, and C may be different, and center lines 153A, 153B, and153C may not be orthogonal to each other.

In some examples, a tolerance may be specified by a cosine value orrange of cosine values. The use of cosine values, in some cases, mayprovide substantial processing efficiencies. As described above, forexample, a minimum cosine value, determined using the referencecoordinate vector as adjacent and sensed coordinate vector ashypotenuse, indicates the range of vectors inside the cone. If a sensedcoordinate vector, in conjunction with the reference coordinate vectorfor a posture cone, produces a cosine value that is less than theminimum cosine value for the posture cone, the sensed coordinate vectordoes not reside within the pertinent posture cone. In this manner, theminimum cosine value may define the outer bound of a range of cosinevalues within a particular posture cone defined in part by a referencecoordinate vector.

While center lines 153A, 153B, 153C of each of the posture cones 154,156, 158, respectively, are shown in FIG. 8B as being substantiallyorthogonal to each other, in other examples, center lines 153A, 153B,and 153C may not be orthogonal to each other, and need not even residein the same plane. Again, the relative orientation of center lines 153A,153B, 153C may depend on the actual reference coordinate vector outputof the posture state sensor of posture state module 86 of IMD 14 whenpatient 12 occupies the respective postures.

In some cases, all of the posture cones may be individually definedbased on actual reference coordinate vectors. Alternatively, in somecases, some posture cones may be defined with reference to one or morereference coordinate vectors for one or more other posture cones. Forexample, lying reference coordinate vectors could be assumed to beorthogonal to an upright reference coordinate vector. Alternatively,lying reference coordinate vectors could be individually determinedbased on sensed coordinate vectors when the patient is in respectivelying postures. Hence, the actual reference coordinate vectors fordifferent postures may be orthogonal or non-orthogonal with respect toone another, and need not reside within the same plane.

In addition to upright cone 154, lying back cone 156, and lying frontcone 158, posture state space 152 may include additional posture cones.For example, a lying right cone may be provided to define a patientposture in which patient 12 is lying on his right side and a lying leftcone may be provided to define a patient posture in which patient 12 islying on his left side. In some cases, the lying right cone and lyingleft cone may be positioned approximately orthogonal to upright cones154, in approximately the same plane as lying back cone 156 and lyingfront cone 158. Moreover, posture state space 152 may include aninverted cone positioned approximately opposite of upright cone 154.Such a cone indicates that the patient's posture is inverted from theupright posture, i.e., upside down.

In some examples, to detect the posture state of a patient, posturestate module 86 of IMD 14 may determine a sensed coordinate vector basedon the posture sensor data generated by one or more posture statesensors, and then analyze the sensed coordinate vector with respect toposture cones 154, 156, 158 of FIG. 8B. For example, in a case in whicha posture cone is defined by a reference coordinate vector and atolerance angle, e.g., tolerance angle “A,” posture state module 86 maydetermine whether the sensed coordinate vector is within upright posturecone 154 by calculating the angle between the sensed coordinate vectorand reference coordinate vector, and then determine whether the angle isless than the tolerance angle “A.” If so, posture state module 86determines that the sensed coordinate vector is within upright posturecone 154 and detects that patient 12 is in the upright posture. Ifposture state module 86 determines that sensed coordinate vector is notwithin upright posture cone 154, posture state module 86 detects thatpatient 12 is not in the upright posture.

Posture state module 86 may analyze the sensed coordinate vector inposture state space 152 with respect to each individual defined posturecone, such as posture cones 156 and 158, in such a manner to determinethe posture state of patient 12. For example, posture state module 86may determine the angle between the sensed coordinate vector andreference coordinate vector of individual posture cones defined for theposture state, and compare the determined angle to the tolerance angledefined for the respective posture cone. In this manner, a sensedcoordinate vector may be evaluated against each posture cone until amatch is detected, i.e., until the sensed coordinate vector is found toreside in one of the posture cones. Hence, a cone-by-cone analysis isone option for posture detection.

In other examples, different posture detection analysis techniques maybe applied. For example, instead of testing a sensed coordinate vectoragainst posture cones on a cone-by-cone basis, a phased approach may beapplied where the sensed coordinate vector is classified as eitherupright or not upright. In this case, if the sensed coordinate vector isnot in the upright cone, posture state module 86 may determine whetherthe sensed coordinate vector is in a lying posture, either by testingthe sensed coordinate vector against individual lying posture cones ortesting the sensed coordinate vector against a generalized lying posturevolume, such as a donut- or toroid-like volume that includes all of thelying postures, and may be defined using an angle or cosine rangerelative to the upright vector, or relative to a modified or virtualupright vector as will be described. In some cases, if lying posturesare defined by cones, the lying volume could be defined as a logical ORof the donut- or toroid-like volume and the volumes of the lying posturecones. If the cones are larger such that some portions extend beyond thelying volume, then those portions can be added to the lying volume usingthe logical OR-like operation.

If the sensed coordinate vector resides within the donut- or toroid-likelying volume, then the sensed coordinate vector may be tested againsteach of a plurality of lying posture cones in the lying volume.Alternatively, the posture detection technique may not use lying cones.Instead, a posture detection technique may rely on a proximity testbetween the sensed coordinate vector and each of the referencecoordinate vectors for the respective lying postures. The proximity testmay rely on angle, cosine value or distance to determine which of thelying posture reference coordinate vectors is closest to the sensedcoordinate vector. For example, the reference coordinate vector thatproduces the largest cosine value with the sensed coordinate vector ashypotenuse and the reference coordinate vector as adjacent is theclosest reference coordinate vector. In this case, the lying postureassociated with the reference coordinate vector producing the largestcosine value is the detected posture. Hence, there are a variety of waysto detect posture, such as using posture cones, using an upright posturecone with lying volume and lying posture cone test, or using an uprightposture cone with lying volume and lying vector proximity test.

As a further illustration of an example posture detection technique,posture state module 86 may first determine whether patient 12 isgenerally in a lying posture state or upright posture state by analyzingthe sensed coordinate vector in posture state space 152 with respect toan axis 153A for the upright posture state. Axis 153A may correspond tothe upright reference coordinate vector. For example, angle “A” may beused to define upright posture cone 154, as described above, and angles“D” and “E” may be used to define the vector space in which patient 12may be generally considered to be in the lying posture state, regardlessof the particular posture state cone, e.g., lying front cone 158, lyingback cone 156, lying right cone (not shown), or lying left cone (notshown), in which the sensed coordinate vector falls.

If it is determined that a sensed coordinate vector is not within anangle A of the axis 153A, then it may be determined that the patient isnot in the upright posture indicated by the upright posture cone. Inthis case, it may next be determined whether a sensed coordinated vectoris generally in a lying posture space volume, which may be consideredsomewhat donut- or toroid-like, and may be defined relative to theupright reference coordinate vector 153A. As shown, angles “D” and “E”define the minimum and maximum angle values, respectively, that a sensedvector may form with respect to axis 153A of patient 12 for adetermination to be made that the patient is generally in the lyingposture state. Again, cosine values may be used instead of angles todetermine the positions of sensed coordinate vectors relative to posturecones or other posture volumes, or relative to reference coordinatevectors.

As illustrated, angles “D” and “E” may be defined with respect tovertical axis 153A (which may correspond to an upright referencecoordinate vector), which is the reference coordinate vector for theupright posture cone, rather than with respect to a reference coordinatevector of a lying posture state cone. If a sensed vector is within theangular range of D to E, relative to axis 153A, then it can bedetermined by posture state module 86 that the patient is generally in alying posture. Alternatively, in some examples, an angle C could bedefined according to a generally horizontal axis 153C (which maycorrespond to one of the lying reference coordinate vectors). In thiscase, if a sensed vector is within angle C of axis 153C, it can bedetermined by posture state module 86 that the patient is in a lyingposture. In each case, the region generally defining the lying posturestate may be referred to as a posture donut or posture toroid, ratherthan a posture cone. The posture donut may generally encompass a rangeof vectors that are considered to be representative of various lyingdown postures.

As an alternative, posture state module 86 may rely on cosine values ora range of cosine values to define the posture donut or toroid withrespect to axis 153A. When the sensed vector falls within the vectorspace defined by axis 153A and angles “D” and “E”, or produces a cosinevalue with the reference coordinate vector 153A in a prescribed range,posture state module 86 may determine that patient 12 is generally in alying posture state. For example, if the sensed vector and referencecoordinate vector 153 produce a cosine value in a first range, theposture is upright. If the cosine value is in a second range, theposture is lying. If the cosine value is outside of the first and secondranges, the posture may be indeterminate. The first range may correspondto the range of cosine values that would be produced by vectors inposture cone 154 defined by angle A, and the second range may becorrespond to cosine values that would be produced by vectors in theposture donut defined by angles D and E.

When the sensed vector fall within the vector space defined by axis 153Aand angles “D” and “E”, as indicated by angle or cosine value, posturestate module 86 may then determine the particular lying posture stateoccupied by patient 12, e.g., lying front, lying back, lying right, orlying left. To determine the particular lying posture state occupied bypatient 12, posture state module 86 may analyze the sensed vector withrespect to reference coordinate vectors for individual lying posturestate cones, e.g., lying front cone 156, lying back cone 158, lyingright cone (not shown), and lying left cone (not shown), using one moretechniques previously described, such as angle or cosine techniques. Forexample, posture state module 86 may determine whether the sensedcoordinated vector resides within one of the lying posture state conesand, if so, select the posture state corresponding to that cone as thedetected posture state.

FIG. 8C illustrates an example posture state space 155 that is athree-dimensional space substantially similar to posture state space 152of FIG. 8B. Posture state space 155 includes upright posture cone 157defined by reference coordinate vector 167. The tolerance that definesupright posture cone 157 with respect to reference coordinate vector 167may include a tolerance angle or cosine value, as described above. Incontrast to determining whether a sensed coordinate vector resides in alying cone, FIG. 8C illustrates a method for detecting a lying posturebased on proximity of a sensed coordinate vector to one of the referencecoordinate vectors for the lying postures.

As shown in FIG. 8C, posture state space 155 includes four referencecoordinate vectors 159, 161, 163, 165, which are associated with lyingleft, lying right, lying front, and lying back posture states,respectively. Posture state module 86 may have defined each of the fourreference coordinated vector 159, 161, 163, 165 based on the output ofone or more posture sensors while patient 12 occupied each of thecorresponding posture states. Unlike lying front and lying back posturecones 158, 156 in the example of FIG. 8B, the posture state referencedata for the four defined posture states corresponding to referencevectors 159, 161, 163, 165 need not include angles defined relative tothe respective reference vector in a manner that defines a posture cone.Rather, as will be described below, the respective posture statereference vectors may be analyzed with respect to one another in termsof cosine values to determine which particular reference coordinatevector is nearest in proximity to a sensed coordinate vector.

In some examples, to determine the posture state of patient 12, posturestate module 85 may determine whether a sensed coordinate vector iswithin upright posture cone 157 by analyzing the sensed coordinatevector in view of the tolerance angle or cosine value(s) defined withrespect to upright posture reference coordinate vector 167, or whetherthe sensed vector is within a posture donut or toroid defined by a rangeof angles (as in FIG. 8B) or cosine values with respect to uprightposture reference coordinate vector 167, in which case posture statemodule 86 may determine that patient 12 is in a general lying posturestate.

If posture state module 86 determines that patient 12 is occupying ageneral lying posture state, posture state module 86 may then calculatethe cosine value of the sensed coordinate vector with respect to eachlying reference coordinate vectors 159, 161, 163, 165. In such a case,posture state module 86 determines the particular lying posture state ofpatient 12, i.e., lying left, lying right, lying front, lying back,based on which cosine value is the greatest of the four cosine values.For example, if the cosine value calculated with the sensed vector asthe hypotenuse and the lying front reference vector 163 as the adjacentvector is the largest value of the four cosine values, the sensed vectormay be considered closest in proximity to lying front reference vectorout of the four total reference vectors 159, 161, 163, 165. Accordingly,posture state module 85 may determine that patient 12 is occupying alying front posture state.

In some examples, posture state module 86 may determine whether patient12 is generally in a lying posture state based on the relationship of asensed vector to upright reference vector 167. For example, as describedabove, a lying posture donut or toroid may be defined with respect toupright posture reference vector 167, e.g., using angles D and E as inFIG. 8B. Such a technique may be appropriate when lying posturereference vectors 159, 161, 163, 165 define a common plane substantiallyorthogonal to upright posture reference vector 167. However, the lyingposture reference vectors 159, 161, 163, 165 may not in fact beorthogonal to the upright reference coordinate vector 167. Also, thelying posture reference vectors 159, 161, 163, 165 may not reside in thesame plane.

To account for non-orthogonal reference vectors, in other examples, alying posture donut or toroid may be defined with respect to a modifiedor virtual upright reference vector 169 rather than that actual uprightposture reference vector 167. Again, such a technique may be used insituations in which the lying reference vectors 159, 161, 163, 165 arenot in a common plane, or the common plane of reference vector 159, 161,163, 165 is not substantially orthogonal to upright reference vector167. However, use of the example technique is not limited to suchsituations.

To define virtual upright reference vector 169, posture state module 86may compute the cross-products of various combinations of lyingreference vectors 159, 161, 163, 165 and average the cross productvalues. In the example of FIG. 8C, posture state module 86 may computefour cross products and average the four cross product vectors to yieldthe virtual upright vector. The cross product operations that may beperformed are: lying left vector 159×lying back vector 165, lying backvector 165×lying right vector 161, lying right vector 161×lying frontvector 163, and lying front vector 163×lying left vector 159. Each crossproduct yields a vector that is orthogonal to the two lying referencevectors that were crossed. Averaging each of the cross product vectorsyields a virtual upright reference vector that is orthogonal to lyingplane 171 approximately formed by lying reference vectors 159, 161, 163,165.

Using virtual upright reference vector 169, posture state module 86 maydefine a lying posture donut or toroid in a manner similar to thatdescribed with respect to upright reference vector 167, but instead withrespect to virtual upright reference vector 169. In particular, whenposture state module 86 determines that the patient is not in theupright posture, the posture state module determines whether the patientis in a lying posture based on an angle or cosine value with respect tothe virtual upright reference vector 169.

Posture state module 86 may still determine whether patient 12 is in anupright posture state using upright posture cone 157. If posture statemodule 86 determines that patient 12 is occupying a general lyingposture state based on the analysis of the sensed coordinate vector withrespect to virtual upright reference vector 169, posture state module 86may then calculate the cosine value of the sensed coordinate vector (ashypotenuse) with respect to each lying reference coordinate vectors 159,161, 163, 165 (as adjacent).

In such a case, posture state module 86 determines the particular lyingposture state of patient 12, i.e., lying left, lying right, lying front,lying back, based on which cosine value is the greatest of the fourcosine values. For example, if the cosine value calculated with thelying front reference vector 163 is the largest value of the four cosinevalues, the sensed vector may be considered closest in proximity tolying front reference vector out of the four total reference vectors159, 161, 163, 165. Accordingly, posture state module 85 may determinethat patient 12 is occupying a lying front posture state.

Additionally, posture state definitions are not limited to posturecones. For example, a definition of a posture state may involve aposture vector and a tolerance, such as a maximum distance from theposture vector. So long as a detected posture vector is within thismaximum distance from the posture vector that is included in thedefinition of the posture state, patient 12 may be classified as beingin that posture state. This alternative method may allow posture statesto be detected without calculating angles, as is exemplified above inthe discussion related to posture cones.

Further to the foregoing, posture states may be defined that arespecific to a particular patient's activities and/or profession. Forinstance, a bank teller may spend a significant portion of his workingday leaning forward at a particular angle. A patient-specific “LeaningForward” posture state including this angle may be defined. The coneangle or other tolerance value selected for this posture state may bespecific to the particular posture state definition for this patient. Inthis manner, the defined posture states may be tailored to a specificuser, and need not be “hard-coded” in the IMD.

In some examples, individual posture states may be linked together,thereby tying posture states to a common set of posture reference dataand a common set of therapy parameter values. This may, in effect, mergemultiple posture cones for purposes of posture state-based selection oftherapy parameter values. For example, all lying posture state cones(back, front, left, right) could be treated as one cone or adonut/toroid, e.g., using a technique the same as or similar to thatdescribed with respect to FIGS. 8B and 8C to define a donut, toroid orother volume. One program group or common set of therapy parametervalues may apply to all posture states in the same merged cone,according to the linking status of the posture states, as directed viaexternal programmer 20.

Merging posture cones or otherwise linking a plurality of posture statestogether may be useful for examples in which a common set of therapyparameter values provides efficacious therapy to patient 12 for theplurality of posture states. In such an example, linking a plurality ofposture states together may help decrease the power consumption requiredto provide posture-responsive therapy to patient 12 because thecomputation required to track patient posture states and provideresponsive therapy adjustments may be minimized when a plurality ofposture states are linked together.

Linking of posture states also may permit a therapy parameter valueadjustment in one posture state to be associated with multiple posturestates at the same time. For example, the same amplitude level for oneor more programs may be applied to all of the posture states in a linkedset of posture states. Alternatively, the lying down posture states mayall reside within a “donut” or toroid that would be used instead ofseparate comes 156 and 158, for example. The toroid may be divided intosectional segments that each correspond to different posture states,such as lying (back), lying (front), lying (right), lying (left) insteadof individual cones. In this case, different posture reference data andtherapy parameter values may be assigned to the different sectionalsegments of the toroid.

FIG. 9 is a conceptual diagram illustrating an example user interface168 of a patient programmer 30 for delivering therapy information topatient 12. In other examples, a user interface similar to userinterface 168 may also be shown on clinician programmer 60. In theexample of FIG. 9, display 36 of patient programmer 30 provides userinterface 168 to the user, such as patient 12, via screen 170. Screen170 includes stimulation icon 174, IMD battery icon 176, programmerbattery icon 178, navigation arrows 180, automatic posture response icon182, group selection icon 184, group identifier 186, program identifier188, amplitude graph 190, and selection box 192. User interface 168provides information to patient 12 regarding group, program, amplitude,and automatic posture response status. User interface 168 may beconfigurable, such that more or less information may be provided topatient 12, as desired by the clinician or patient 12.

Selection box 192 allows patient 12 to navigate to other screens,groups, or programs using navigation arrows 180 to manage the therapy.In the example, of screen 170, selection box 192 is positioned so thatpatient 12 may use arrows 44 and 48 to move to the automatic postureresponse screen, the volume screen, the contrast or illumination screen,the time screen, and the measurement unit screen of patient programmer30. In these screens, patient 12 may be able to control the use of theautomatic posture response feature and adjust the patient programmer 30features. Patient 12 may only adjust the features surrounded byselection box 192.

Group identifier 186 indicates one of possibly several groups ofprograms that can be selected for delivery to patient 12. Groupselection icon 184 indicates whether the displayed group, e.g., group Bin FIG. 9, is actually selected for delivery to patient 12. If apresently displayed group is selected, group selection icon 184 includesa box with a checkmark. If a presently displayed group is not selected,group selection icon 184 includes a box without a checkmark. To navigatethrough the program groups, a user may use control pad 40 to moveselection box 192 to select the group identifier 186 and then usecontrol pad 40 to scroll through the various groups, e.g., A, B, C, andso forth. IMD 14 may be programmed to support a small number of groupsor a large number of groups, where each group contains a small number ofprograms or a large number of programs that are deliveredsimultaneously, in sequence, or on a time-interleaved basis.

For each group, group selection icon 184 indicates the appropriatestatus. For a given group, program identifier 188 indicates one of theprograms associated with the group. In the example of FIG. 9, no programnumber is indicated in program identifier 188 because all of theprograms' amplitudes are shown in each bar of amplitude graph 190. Solid(black) portions of the bars indicate the relative amplitude IMD 14currently is using to deliver stimulation therapy to patient 12, whileopen (white) portions of the bars indicate the remaining amplitudeavailable to each program. In some embodiments, numerical values of eachprogram's amplitude may be shown in addition to or in place of amplitudegraph 190. In other embodiments of user interface 168 specific to drugdelivery using IMD 26, amplitude graph 190 may show the flow rate ofdrugs, frequency of bolus delivery to patient 12, or other parametervalues. This information may be shown in numerical format as well.Patient 12 may encompass group selection icon 184 with selection box 192to scroll between the different groups of programs.

Automatic posture response icon 182 indicates that IMD 14 is generallyactivated to automatically change therapy to patient 12 based upon theposture state detected by posture state module 86. In particularly,automatic posture responsive therapy may involve adjusting one or moretherapy parameter values, selecting different programs or selectingdifferent program groups based on the detected posture state of thepatient. However, automatic posture response icon 182 is not presentnext to group identifier 186. Therefore, group “B” does not haveautomatic posture responsive therapy activated for any of the programswithin group “B.”

Some groups or individual programs in groups may support automaticposture responsive therapy. For example, automatic adjustment of one ormore therapy parameters in response to posture state indication may beselectively activated or deactivated based on settings entered by aclinician, or possibly patient 12. Hence, some programs or groups may beconfigured for use with posture responsive therapy while other programsor groups may not be configured for use with posture responsive therapy.In some cases, if posture responsive therapy supported by the automaticposture response feature is desired, patient 12 may need to switchtherapy to a different group that has automatic posture responsivetherapy activated for IMD 14 to adjust therapy according to the patient12 posture state.

FIG. 10 is a conceptual diagram illustrating an example user interface168 of a patient programmer 30 for delivering therapy information thatincludes posture information to the patient. In other examples, userinterface 168 may also be shown on clinician programmer 60. In theexample of FIG. 10, display 36 of patient programmer 30 provides userinterface 168 to the user, such as patient 12, via screen 194. Screen194 includes stimulation icon 174, IMD battery icon 176, programmerbattery icon 178, and automatic posture response icon 182, similar toscreen 170 of FIG. 9. In addition, screen 194 includes group selectionicon 184, group identifier 186, supplementary posture state indication202, program identifier 196, posture state indication 200, amplitudevalue 204, selection box 192, and selection arrows 180. User interface168 provides information to patient 12 regarding group, program,amplitude, automatic posture response status, and posture stateinformation. More or less information may be provided to patient 12, asdesired by the clinician or patient 12.

Group identifier 186 indicates that group “B” is active, and automaticposture response icon 182 indicates group “B” (containing one or moreprograms) is activated to allow IMD 14 to automatically adjust therapyaccording to the patient posture state. Program identifier 196illustrates the information regarding program “1” of group “B” isdisplayed on screen 194, such as amplitude value 204 illustrating thecurrent voltage amplitude of program “1” as 2.85 Volts. Patient 12 mayscroll through different programs of the group by using navigationarrows 180 via arrows 44 and 48 of control pad 40.

In addition, posture state indication 200 shows that IMD 14 has detectedthat patient 12 is in the upright or standing posture. Supplementaryposture state indication 202 supplements posture state indication 200 byillustrating in one or more words to patient 12 the exact posture beingdetected by posture state module 86 of IMD 14 at a given time. Posturestate indication 200 and supplementary posture state indication 202change according to the sensed, or detected, posture state detected byIMD 14. The posture state may be communicated to external programmer 20immediately when IMD 14 detects a posture change, or communicatedperiodically or non-periodically by IMD 14 unilaterally or uponreceiving a request from programmer 20. Accordingly, the posture stateindication 200 and/or supplementary posture state indication 202 mayrepresent a current, up-to-the minute status, or a status as of the mostrecent communication of posture state from IMD 14. Posture stateindication 200 is shown as a graphical representation, but the posturestate indication may alternatively be presented as any one of a symbolicicon, a word, a letter, a number, an arrow, or any other representationof the posture state. In some cases, posture state indication 200 may bepresented without supplementary posture state indication 202.

Selection box 192 indicates that patient 12 views other programs withingroup “B” using selection arrows 208. Selection box 192 may be moved toselect other screen levels with control pad 40 in order to navigatethrough other stimulation groups or adjustable elements of the therapy.When patient 12 selects a different program with control pad 40, programidentifier 196 will change number to correctly identify the currentprogram viewed on screen 194. In a different screen (not shown) of userinterface 168, patient 12 may be allowed to view certain objectivitydata, such as sleep quality information or proportional postureinformation available to the clinician as described herein. Theclinician may enable to disable this feature depending upon whetherpatient 12 would benefit from being able to view this objective posturestate information.

In addition to graphical, textual or other visible indications ofposture state, external programmer 20 may present audible and/or tactileindications of posture state via any of a variety of audible or tactileoutput media. An audible indication may be spoken words stating aposture state, or different audible tones, different numbers of tones,or other audible information generated by the programmer to indicateposture state. A tactile indication may be, for example, differentnumbers of vibratory pulses delivered in sequence or vibratory pulses ofdifferent lengths, amplitudes, or frequencies.

FIG. 11 is a conceptual diagram illustrating an example user interface208 for presenting graphical proportional posture information to a userfor each of several days of a therapy session. User interface 208 isdescribed as generally being displayed by clinician programmer 60.However, user interface 208 may also be displayed by patient programmer30 or some other external programmer 20 or remote device. In any case,user interface 208 displays objective data derived from posture statedata detected by a posture state module 86 based upon the posture andactivity of patient 12. The posture state module 86 may reside within anIMD that delivers therapy to the patient, or within another device thatis implanted within or external to a patient.

In the example of FIG. 11, screen 210 of user interface 208 presentsposture duration graph 236, operational menu 224, networking icon 214,printer icon 216, IMD communication icon 218, programmer battery icon220, stimulation status icon 222, patient data icon 226, data recordingicon 228, device status icon 230, programming icon 232, and datareporting icon 234. In addition, screen 210 includes time intervals 238,detail input note 239, posture state key 240, and sleep quality button242. Screen 210 may be accessed by selecting data recording icon 228 toopen a drop down menu that allows the user to select one of multipledifferent screens. The user may select “objectification” or some othertext or icon that symbolizes access to proportional posture informationand screen 210.

Screen 210 includes multiple menus and icons common to other screens ofuser interface 208. Operational menu 224 is a button that the user mayselect to view multiple options or preferences selectable by the user.Operational menu 224 may provide preferences for clinician programmer 60instead of therapy specific information. Networking icon 214 is shown asgrayed out to indicate that clinical programmer 60 is not currentlyconnected to a network. When networking icon 214 is shown fully,clinician programmer 60 is connected to a network. Printer icon 216indicates when clinician programmer 60 is connected to a printer. Whenprinter icon 216 is grayed out as shown in FIG. 11, there is no printerconnected to clinician programmer 60.

Further, IMD communication icon 218 is shown as indicating thatclinician programmer is not in communication with IMD 14 because theicon includes a slash through the IMD representation. The slash isremoved when clinician programmer 60 has established a communicationlink to IMD 14. In addition, programmer battery icon 220 indicates thecurrent charge level of the battery contained within clinicianprogrammer 60. Stimulation status icon 222 indicates to the user whenstimulation is being delivered to patient 12. In the example of FIG. 11,stimulation is not currently being delivered, but stimulation statusicon 222 may include an electrical bolt through the IMD representationwhen stimulation is being delivered by IMD 14.

Screen 210 also provides menu options related to stimulation therapy ofpatient 12. Patient data icon 226 allows the user to enter and reviewdata related to the status of and the condition of patient 12. Datarecording icon 228 allows the user to navigate to other screens to enterdata recording preferences and review stored data. Device status icon230 allows the user to view operational status of components of IMD 14,such as electrodes, leads, batteries, and any discovered problems.Programming icon 232 allows the user to navigate to programming screensthat define the stimulation therapy parameters used to deliverstimulation to patient 12. In addition, data reporting icon 234 allowsthe user to view and print reports of patient 12 progress and othertherapy information.

Posture duration graph 236 includes proportional posture informationbased on posture state data stored from detected posture states ofpatient 12. The proportional posture information may be generated basedon durations for which the patient occupied each of a plurality ofposture states based on the posture state data in a given time interval.In particular, the proportional posture information may be based on thedurations indicating proportional amounts of the time interval in whichthe patient occupied each of the posture states. The proportionalposture information may be presented in a graphical form, such as a bargraph. The graph may include posture bars for a plurality of timeintervals. Each posture bar includes bar segments indicatingproportional amounts of the respective time interval in which thepatient occupied each of the posture states.

Posture duration graph 236 includes the percentage of time, or posturedurations, for each of two or more posture states during given timeintervals. In the example of FIG. 11, posture duration graph 236indicates that percentage of time during which the patient occupied eachof three posture states during each of the indicated days defined bytime intervals 238. In particular, each bar in the bar graph correspondsto one of the time intervals, and each bar includes multiple barsegments, where each segment indicates the proportional amount of timethe patient occupied a particular posture state in relation to theoverall amount of time of the respective one of time intervals 238. Timeintervals 238 may be days, weeks, months, years, durations between twoclinician programming sessions, or some other period of time. In theexample of FIG. 11, each time interval is a particular day. Each of timeintervals 238 may also be of varying time durations. Posture durationgraph 236 is generally described as indicating respective percentages oftime in which patient 12 resides in a given posture state during a timeinterval. Percentages, absolute times, or other metrics may be used andobtained in variety of ways.

For example, a posture detection module, e.g., posture state module 86,may sample the posture state at regular sampling intervals, and thendetermine the percentage of time in which patient 12 occupied particularposture state by adding up the number of samples associated with thatposture state versus the total number of samples obtained during thetime interval. In this case, if Y posture state samples are taken withinan interval, a posture state that is detected X times may be expressedin terms of a percentage X/Y.

As an alternative example, samples may be time-stamped or tracked in atimer or counter such that the elapsed time between a sample indicatinga transition to a particular posture state and a sample indicating atransition away from the particular posture state can be computed,indicating a duration that the patient resided in the posture state. Inthis case, total elapsed time can be calculated over the time interval,taking into account multiple transitions to and from the posture state,if applicable. Alternatively, instead of using time stamps, a timer orcounter may be activated when the patient 12 transitions to a posturestate and deactivated when the patient transitions away from the posturestate.

As a further example, the number of samples for a given posture statemay be multiplied by a known amount of time between consecutive samplesin order to compute an overall time in the posture state. If there are“n” samples for a given posture, and a time of “m” seconds separatesconsecutive samples, then the total time in the posture may bedetermined to be “n” multiplied by “m” seconds.

In addition to overall time during a time interval, individual durationswithin a posture, i.e., after transitioning to and before transitioningaway from the posture, may be tracked using techniques similar to thosedescribed above. Many different techniques may be used to calculate thepercentages of time in which a patient 12 resides in different posturestates over a given time interval. Such techniques may be implementedwithin IMD 14, external programmer 20, or a combination of both.Accordingly, the examples described above are provided for purposes ofillustration and without limitation of the techniques broadly describedin this disclosure.

Posture state key 240 defines each of the posture segments (i.e.,Upright and Active, Upright, Lying Down) that make up the posture barfor each time interval 238. A greater or lesser number of posture statesmay be tracked and expressed in graph 236. In addition, in someembodiments, a user may request refinement of some data. For example, auser may wish to know, among the lying down posture states, thepercentage of time in which the patient occupied the lying down back,lying down front, lying right and lying left posture states. As anillustration, the programmer may permit the user to click on the lyingportion of the graph, e.g., with a stylus, in order to view thepercentages for the lying down sub-states. In response, externalprogrammer 20 may display this additional information.

As shown in FIG. 11, the percentage of time that patient 12 spent ineach posture state changed between each day, as indicated by thedisplayed proportional posture information. Time intervals 238 may beconsecutive days. Alternatively, as shown in FIG. 11, some of timeintervals 238 may be non-consecutive days, or other time intervals, suchas weeks, months, or therapy sessions of varying length. The days usedas time intervals 238 may have been selected by the clinician orautomatically selected by processor 104 based upon the proportionalposture information or the amount of time stimulation therapy was beingdelivered. For example, processor 104 may not present proportionalposture information for time intervals in which stimulation wasdelivered for less than ten percent of the time interval, as suchinformation may be less meaningful for purposes of evaluatingtherapeutic efficacy. In other cases, however, such information mayprovide a helpful set of baseline control data, e.g., for comparisonwith information obtained when stimulation is delivered for greater thanten percent of a time interval.

As shown on posture duration graph 236, for Jun. 13, 2008(“06/13/2008”), proportional posture graph 236 indicates that patient 12was in the lying down posture 60 percent of the time, the uprightposture 35 percent of the time, and the upright and active posture stateonly 5 percent of the time. As mentioned above, the lying down posturestate may include: lying front, lying back, lying right, and lying left.The upright and active posture state indicates that patient 12 wasupright in addition to being engaged in some sort of activity, such aswalking or running, as opposed to remaining stationary. In contrast,posture duration graph 236 shows that, for Jun. 19, 2008, six dayslater, patient 12 was in the lying down posture 30 percent of the time,the upright position 55 percent of the time, and the upright and activeposture 15 percent of the time. The clinician may recognize a trendindicating that patient 12 is in the upright posture state for a muchgreater duration than when compared to the previous days. In some cases,the clinician may infer from such data that patient 12 may be respondingwell to effective therapy by being able to be up and out of bed for agreater percentage of the time.

Instead of or in addition to percentages, posture duration graph 236 mayprovide times in hours and minutes for each posture state. In addition,the lying down posture state may be split into two or more of all lyingdown postures, such as lying front, lying back, lying right, and lyingleft, either in a normal mode or upon receipt of user input requestingrefinement of the lying down posture data, as mentioned above. Further,posture duration graph 236 may be altered by the clinician to show lessthan all of the posture states in order to more easily compare fewerposture states over time durations 238. Posture duration graph 236 mayalso be modified to include more or less than four time intervals at onetime.

The objectivity of posture duration graph and proportional postureinformation may allow the clinician to monitor trends in the response ofpatient 12 to therapy, such as posture state-responsive therapy, withoutburdening patient 12 with the need to manually and, more subjectively,log their postures and activities throughout the day. In addition to thesubjective nature of input by patient 12, entry of information bypatient 12 is commonly plagued with errors, intentional or accidental,that can limit the clinician's access to accurate information for use inmore effectively treating patient 12. Posture state data, includingactivity data, may be difficult for patient 12 to accurately determine.Logging posture state data may be especially difficult, or evenimpossible, during sleep. Therefore, generating proportional postureinformation and presenting the information to the clinician via userinterface 208 may be beneficial. In particular, user interface 208 maypresent the proportional posture information for multiple time intervalssimultaneously so that the clinician may observe a trend in posturestates occupied by the patient over the multiple time intervals. Theability to observe proportional posture information for multiple timeintervals to develop a trend may be especially useful when the clinicianadjusts therapy parameters for different time intervals. Moreover, theclinician may select sleep quality button 242 in order to view specificsleep quality information generated from the posture state data, asdescribed in FIGS. 17-20. In other words, the clinician may view generalposture state information or selectively view specific posture stateinformation, such as lying posture states, to evaluate sleep quality.

After the clinician views posture duration graph 236, the clinician maydesire to view the detailed durations of each posture state used tocreate the posture duration graph. Detail input note 239 informs theclinician to “Click on BarChart for details.” As mentioned above, detailinput note 239 or another similar input medium may permit the user torefine the information, e.g., to view lying states in more detail and/orview sleep quality information, which also may include the lying states.If the clinician clicks or selects a location anywhere within postureduration graph 236, processor 104 may present the calculated posturestate durations for each of the time intervals. In other examples,screen 210 may provide a customize icon that the clinician may select tomodify how user interface presents the proportional posture informationon posture duration graph 236.

In general, according to the example of FIG. 11, a programmer 20 or IMD14 may obtain posture state data sensed by the IMD for a patient duringdelivery of therapy by the medical device, and determining durations forwhich the patient occupied each of a plurality of posture states basedon the posture state data. Based on the durations, the programmer 20 orIMD 14 may proportional posture information for a plurality of differenttime intervals. The proportional posture information for each of thetime intervals indicates proportional amounts of the respective timeinterval in which the patient occupied the posture states. As shown inFIG. 11, the proportional posture information for each of the timeintervals may be presented to a user via a user interface of aprogrammer.

FIG. 12 is a conceptual diagram illustrating an example user interface208 for simultaneously presenting detailed posture state durations foreach time interval of FIG. 11. Screen 244 of user interface 208 presentsthe calculated posture state durations for each of the posture stateswithin each of the time intervals. Screen 244 also presents heading 245,time intervals 246, posture states 248A, 248B, 248C, 248D, 248E and 248F(collectively “posture states 248”), and calculated posture statedurations 250A, 250B, 250C, 250D, 250E and 250F (collectively “posturedurations 250”) for each of posture states 248. In addition, screen 244presents return button 252 and sleep quality button 242.

Heading 245 presents screen information that explains what data is beingpresented in screen 244, including the units of the posture durations250. Just as in screen 210, time intervals 246 are the specified daysfor which the proportional posture information is provided. Each ofposture states 248 are provided, upright, upright and active, lyingback, lying front, lying right, and lying left. Screen 244 breaks aparteach of the lying down postures to provide more detailed information tothe clinician than shown in posture duration graph 236 of FIG. 11.Alternatively, refinement of the lying down posture states may beexpressed by showing additional bars in graph 236 of FIG. 11, or showingsub-bars indicating lying back, lying front, lying right, and lying leftposture states and associated percentages within the lying posture statebar of FIG. 11. In the example of FIG. 12, all of posture durations 250are provided in hours and minutes for each of the days specified in timeintervals 246. In this example, posture durations 250 are not averages,but the actual, total duration for which patient 12 occupied eachposture state during the respective days.

If the clinician again wants to view posture duration graph 236, theclinician may select return button 252 (“Show BarChart”). This inputreceived from the clinician may be considered to be a proportionalposture input to again initiate the presentation of posture durationgraph 236. Again, the clinician may select sleep quality button 242 toview sleep quality information. In some examples, the clinician may befurther able to view posture state frequency values for each of theposture states in each time interval. The posture state frequency valueis the number of times that patient 12 was engaged in each posture state248. The number of times may refer to the number of discrete,noncontiguous times the patient occupied a posture state. When patient12 occupies a first, given posture state, then transitions away to oneor more other posture state, and then transitions back to the firstposture state, patient 12 has occupied the first posture state twice,such that the posture state frequency value for the first posture stateis two.

In addition, the clinician may be able to scroll through each of theindividual posture state durations throughout the day that make up eachof the total posture durations 250. If patient 12 occupied a firstposture state two times for “n” minutes and “m” minutes, respectively,the user may view the total duration “n”+“m”, or the individualdurations “n” and “m”. Also, in some cases, the programmer may permitthe user to view the time of day (or time within the time interval) atwhich the individual durations occurred. In examples where timeintervals 246 are greater than a day, posture durations 250 may beaveraged for each day.

FIG. 13A is a conceptual diagram illustrating an example user interfacefor presenting graphical proportional posture information averaged forseveral months. Substantially similar to screen 210 of FIG. 11, screen254 of user interface 208 displays objective data derived from posturestate data detected by posture state module 86 based upon the postureand activity of patient 12. However, the proportional posture data maybe averaged over a time interval of one month, for example. In thiscase, posture data may be obtained for multiple time sub-intervalswithin the month, such as days or weeks, and then averaged for the monthto provide a monthly average of each posture state duration.Alternatively, in other embodiments, posture data may be obtained overthe entire monthly time interval without calculating the average datafrom sub-intervals within the respective time interval.

Posture duration graph 256 includes proportional posture informationthat includes the average posture durations for each of three posturestates each day during each of the indicated months defined by timeintervals 258. In the example of FIG. 13A, the months are 03/08 (March2008), 04/08 (April 2008), and so forth. Posture state key 260 defineseach of the posture segments that make up the posture bar for each timeinterval 258. As shown in FIG. 13A, the average percentage of time thatpatient 12 spent in each posture state every day of the month changedbetween each of the consecutive months shown as time intervals 258. Themonths used as time intervals 238 may have been selected by theclinician or automatically selected by processor 104 based upon theproportional posture information, most recent posture state data, or theamount of time stimulation therapy was being delivered. For example,processor 104 may be configured to not present proportional postureinformation for time intervals in which stimulation was delivered forless than ten percent of each day in the time interval.

Posture duration graph 256 illustrates a trend indicating that patient12 is in the upright posture state for a much greater duration in morerecent months than in previous months of the therapy. Therefore, it maybe possible to infer that patient 12 is responding well to effectivetherapy by being able to be up and out of bed more frequently or forgreater durations of time. Alternatively, the clinician may beattempting to treat patient 12 so that bed rest is tolerable withstimulation therapy. In this example, the more current therapy is notbeing effective at allowing patient 12 to remain lying down for longperiods of time. Similar to screen 210, detail input note 259 informsthe clinician to “Click on barchart for details.” If the clinicianclicks or selects a location anywhere within posture duration graph 256,processor 104 may present the average calculated posture state durationsfor each of the time intervals 258.

FIG. 13B is a conceptual diagram illustrating an example user interface208 for presenting detailed posture state durations for each month ofFIG. 13A. Screen 262 is substantially similar to screen 244 of FIG. 12.Screen 262 of user interface 208 presents the average calculated posturestate durations for each of the posture states within each of the timeintervals 258 from FIG. 13A. Screen 262 also presents heading 264, timeintervals 266, posture states 268A, 268B, 268C, 268D, 268E and 268F(collectively “posture states 268”), and calculated posture statedurations 270A, 270B, 270C, 270D, 270E and 270F (collectively “posturedurations 270”) for each of posture states 268. In addition, screen 262presents return button 272 (“Show BarChart”) and sleep quality button242 (“View Sleep Quality Index”).

Heading 264 presents screen information that explains what data is beingpresented in screen 254, including the units of the posture durations270. Time intervals 266 are the specified months for which theproportional posture information is averaged for each day within themonth, the same time intervals from FIG. 13A. Each of posture states 268are provided: upright, upright and active, lying back, lying front,lying right, and lying left. Screen 262 breaks apart each of the lyingdown postures to provide more detailed information to the clinician thanshown in posture duration graph 256 of FIG. 13A. All of posturedurations 270 are provided in hours and minutes as the average amount oftime per day in each time interval that patient 12 was engaged in eachof posture states 268.

If the clinician again wants to view posture duration graph 256 again,the clinician may select return button 272. This input received from theclinician may be considered to be a proportional posture input to againinitiate the presentation of posture duration graph 256. In someexamples, the clinician may be further able to view posture statefrequency value for each of the posture states in each time interval.The posture state frequency value, for posture durations averaged forthe months of time intervals 266, is the number of times that patient 12was engaged in each posture state 268. In some cases, posture durations270 may be configured to present median durations or the most commondurations.

In alternative examples of screen 262, user interface 208 may providetime intervals different than months. For example, the segment durationof each of the time intervals may be several days, weeks, several weeks,several months, years, time between clinician programming sessions, orany other customizable time interval desired by the clinician. The timebetween clinician programming sessions can be referred to as a therapysession. In addition, the time intervals do not need to be consecutive.The clinician or processor 104 may select representative months over along therapy period in order for the clinician to derive any trends fromthe proportional posture information. In other examples, processor 104may associate the therapy parameters used during therapy and presenttime intervals in which different therapy parameters were used. In thismanner, the clinician may be able to compare the effectiveness ofdifferent therapy programs or groups of programs that may have been moreeffective at another point in past stimulation therapy.

FIG. 14A is a conceptual diagram illustrating an example user interface208 that presents screen 263 and graphical proportional postureinformation as posture duration graph 265 for previous therapy sessionsas time intervals. Substantially similar to screens 210 and 254 of FIGS.11 and 13A, respectively, screen 263 of user interface 208 displaysobjective data derived from posture state data detected by posture statemodule 86 based upon the posture and activity of patient 12. However, inthe example of FIG. 14A, the proportional posture data is presented andaveraged over a time interval of one therapy session, rather than afixed, regular time interval such as a day, week or month. In this case,posture state data obtained in therapy sessions between clinicianprogramming sessions is combined and provided as posture duration graph265 with proportional posture information for each of four previoustherapy sessions. The proportional posture information for multiple timeintervals, e.g., multiple therapy sessions, can be presentedsimultaneously to permit a clinician to evaluate proportional posturechanges among different therapy sessions in which IMD 14 may haveapplied different therapy parameters. In general, the length of eachtherapy session is a function of the time between successive programmingsessions, i.e., the time between a previous programming sessions thatsets the parameters for the therapy session and a subsequent programmingsession in which the parameters may be adjusted. Consequently, thelengths of different therapy sessions may be different from one another,rather than fixed in length like fixed time intervals such as days,weeks or months.

The posture state data for each therapy session is analyzed to generatethe proportion of time that patient 12 was engaged in each of theprovided posture states. Although the posture state data may be averagedfor each day, week or month within the therapy session, the overallpercentage of time that patient 12 was engaged in each posture statewould be presented as the same percentage values in posture durationgraph 265. In other words, generation of a daily, weekly or monthlyaverage is possible in the example of FIG. 14A, but the average would bethe same for every day, week or month in the therapy session, as thedata is accumulated over the entire therapy sessions instead of beingtracked for individual days, weeks or months. In the example of FIG.14A, a daily average can be calculated for a given therapy session,e.g., the therapy session between the programming session of 12/29/08and the programming session of 02/09/09, by simply dividing theapplicable value by the number of days in that period.

Posture duration graph 265 includes proportional posture informationthat includes the average posture durations for each of four posturestates each day during each of the indicated therapy sessions defined byclinic leave dates 267 and clinic arrive dates 269. During a therapysession, IMD 14 delivers therapy according to parameters specified inthe previous programming session. In the example of FIG. 14A, clinicleave dates 267 indicate when patient 12 leaves the clinic following aprogramming sessions with new therapy parameters and include 12/29/2008(Dec. 29, 2008), 02/09/2009 (Feb. 9, 2009), and so forth. Clinic arrivedates 269 indicate when patient 12 arrives at the clinic for aprogramming session to receive updates or adjustments to therapyparameters and include 02/09/2009 (Feb. 9, 2009), 03/09/2009 (Mar. 9,2009), and so forth. Although clinic leave dates 267 and clinic arrivedates 269 define consecutive sessions, posture duration graph 265 maypresent non-consecutive sessions selected by external programmer 20,patient 12, or the clinician.

Posture state key 271 defines each of the posture segments that make upthe posture bars of posture duration graph 265. Posture state key 271includes “Mobile,” “Upright,” “Lying,” and “Transition Zone” posturestates. As shown in FIG. 14A, the average percentage of time thatpatient 12 spent in each posture state every day of the therapy sessionchanged between each of the consecutive therapy sessions of postureduration graph 265. The therapy sessions used may have been selected bythe clinician or automatically selected by processor 104 based upon theproportional posture information, most recent posture state data, or theamount of time stimulation therapy was being delivered. For example,processor 104 may be configured to not present proportional postureinformation for time intervals in which stimulation was delivered forless than ten percent of each day in the time interval.

Posture duration graph 256 illustrates a trend over multiple therapysessions indicating that patient 12 is in the lying posture state forless time for each consecutive therapy session. Therefore, it may bepossible to infer that patient 12 is responding well to effectivetherapy by being able to be up and out of bed in an upright posture morefrequently or for greater durations of time. Alternatively, theclinician may be attempting to treat patient 12 so that bed rest is moretolerable with stimulation therapy. In this example, the more currenttherapy may not be effective at allowing patient 12 to remain lying downfor longer periods of time. Detail input 275 informs the clinician thatclicking the “View Details” button may provide more detailedproportional posture information. If the clinician clicks on detailinput 275, processor 104 may present the average calculated posturestate durations for each of the sessions defined by clinic leave dates267 and clinic arrive dates 269.

Info button 273 may provide the user with additional informationregarding the posture data presented in screen 263. For example,clicking on info button 273 may cause user interface 106 to present apop-up window that reminds the user of certain changes to system 10 thatcould have affected the presented posture data. Resetting theorientation of the posture state module, adjusting a posture cone orvector, or otherwise changing how system 10 detects patient posturestates and generates the posture state information may be of interest tothe user. Additionally, information provided to the user by clickinginfo button 273 may include details about how the posture state data wasused to generate the proportional posture information of postureduration graph 265.

FIG. 14B is a conceptual diagram illustrating an example user interface208 for presenting detailed calculations of upright posture durations281 and lying posture durations 285 for each therapy session. Screen 277is substantially similar to screens 244 and 262 of FIGS. 12 and 13B,respectively. Screen 277 of user interface 208 presents the averagecalculated posture state durations for each of the posture states withineach of the therapy sessions identified by clinic leave dates 283A,283B, 283C, and 283D (collectively “clinic leave dates 283) from FIG.14A. Screen 277 also presents heading 279, upright posture durations281, lying posture durations 285, and info button 289. In addition,screen 277 presents chart button 291 (“View Chart”). Again, posturestate information may be displayed for multiple time intervalssimultaneously to permit a clinician to observe a trend, especially whenthe clinician has adjusted therapy parameters of the therapy sessionassociated with the time intervals.

Heading 279 presents screen information that explains what data is beingpresented in screen 277, including the units of the posture durations281 and 285. Clinic leave dates 283 indicate the beginning date of theprovided therapy session, as further defined in screen 263 of FIG. 14A.Upright posture durations 281 provides the average duration of each dayof the respective therapy session that patient 12 engaged in both theupright posture state and the mobile posture state. For example, patient12 spent an average of 30 minutes in the upright posture state and 15minutes in the mobile posture state per day during the session startedon Feb. 9, 2009. Lying posture durations 285 provides the averageduration of each day of the respective therapy session that patient 12engaged in each of the lying back, lying front, lying right, and lyingleft posture states. For example, patient 12 spent an average of 10hours in the lying back posture state, 30 minutes in the lying frontposture state, 30 minutes in the lying right posture state, and 11 hoursin the lying left posture state per day during the session started onFeb. 9, 2009. Each of the averages provided by screen 277 may be roundedto the nearest minute, and all times may be presented in the hours andminutes format.

If the clinician again wants to view posture duration graph 265 (FIG.14A), the clinician may select chart button 291. This input, chartbutton 291, received from the clinician may be considered to be aproportional posture input to again initiate the presentation of postureduration graph 265. In some examples, the clinician may be further ableto view posture state frequency values for each of the posture states ineach time interval. The posture state frequency value, for posturedurations averaged for the specific sessions, is the number of timesthat patient 12 was engaged in each of the posture states of uprightposture durations 281 and lying posture durations 285 in a given timeinterval. In some cases, one or both of upright posture durations 281and lying posture durations 285 may be configured to present mediandurations or the most common durations within each session indicated byclinic leave dates 283.

Info button 289 may provide the user with additional informationregarding the posture data presented in screen 277. For example,clicking on info button 289 may cause user interface 106 to present apop-up window that reminds the user of certain changes to system 10 thatcould have affected the presented posture data. Resetting theorientation of the posture state module, adjusting a posture cone orvector, or otherwise changing how system 10 detects patient 12 posturestates and generates the posture state information may be of interest tothe user.

In alternative examples of screens 263 and 277, user interface 208 mayprovide time intervals different than consecutive therapy sessions. Forexample, the segment duration of each of the time intervals may beseveral days, weeks, several weeks, several months, years, or any othercustomizable time interval desired by the clinician. In addition, thetime intervals do not need to be consecutive. The clinician or processor104 may select representative sessions over a therapy period of manyweeks, months or years in order for the clinician to derive any trendsfrom the proportional posture information. In other examples, processor104 may associate the therapy parameters used during therapy and presenttime intervals in which different therapy parameters were used. In thismanner, the clinician may be able to compare the effectiveness ofdifferent therapy programs or groups of programs that may have been moreeffective at different points during the therapy of patient 12.

In the examples of FIGS. 11-14B, external programmer 20 may configurethe display screen to permit vertical and/or horizontal scrolling sothat additional information can be viewed, e.g., for time intervalsseparated by larger spans of time. Also, the display screen may permitscreen splitting and/or scroll bar splitting, e.g., in a manner similarto word processing and spreadsheet applications, so that portions thatwould not otherwise be visible on the same screen can be made visible inside-by-side or top-and-bottom split screens. As an illustration, asplit screen may permit more effective viewing of information for timeintervals from April 2010 and May 2008.

FIG. 15 is a conceptual diagram illustrating an example user interface208 for presenting graphical proportional posture information inaddition to a posture state frequency value for each posture state.Screen 274 is substantially similar to screen 254 of FIG. 13A. However,screen 274 also presents a posture state frequency value 278, inaddition to the posture duration 280 provided as a percentage and asgraphical posture segment for each posture bar of posture duration graph276. Time intervals 282 may again be consecutive months for which theposture states of patient 12 were recorded; however, other examples mayprovide different time intervals, e.g. therapy sessions defined byclinic visits. In addition, posture state key 284 provides theindication of each posture state.

Posture state frequency value 278 is provided for each posture state ofeach time interval 282. Posture state frequency value 278 is the averagenumber of times patient 12 was engaged in each of the posture statesduring each time interval. In other words, posture state frequency value278 is a count of how frequently patient 12 engaged in each posturestate during an average day of each time interval. For example, theposture bar for June 2008 (“06/08”) indicates that patient 12 wasengaged in the upright, upright and active, and lying posture states foran average of 55 percent, 15 percent and 30 percent of each day duringJune 2008. In addition, posture state frequency value 278 located withinthe bar segment indicates that the upright, upright and active, andlying postures were assumed an average of 35 times, 11 times, and 15times, respectively, during each day in June 2008. In alternativeembodiments, posture state frequency value 278 may be located outside ofeach bar segment, in a separate graph, or be visible only when theclinician selects to view the detailed posture durations.

Posture state frequency values 278 may be beneficial to the clinician indetermining how often patient 12 has tried to engage in a particularposture state. For example, a high posture state frequency value coupledto a small posture duration may indicate that the condition of patient12 is preventing patient 12 from being engaged in the posture state formore than an unacceptably small period of time. Rather, patient 12transitions to the posture state frequently but, in general, transitionsout of the posture state relatively quickly. In this case, the clinicianmay attempt to adjust the stimulation parameters for more efficacioustherapy. Of course, the combinations of posture state frequency valuesand posture durations may only be beneficial to objectively view thebehavior of patient 12 when the clinician understands the condition ofpatient 12 that the stimulation therapy is designed to treat.

FIG. 16A is a conceptual diagram illustrating an example user interface208 for presenting an average quantified number of posture state changesduring select time intervals of therapy. As shown in FIG. 16A, screen286 of user interface 208 provides an activity quality index as activitygraph 288, e.g., an average number of posture state changes for eachtime interval, to aid the clinician in objectively determining theefficacy of the therapy. Activity graph 288 includes activity bars 290and activity value 292 for each of the four time intervals 294 ofsegment durations in months. Each activity bar 290 is a graphicalrepresentation of the average quantified number of posture state changesduring each time interval. Accordingly, each activity value 292 is therespective numerical representation. Done button 296 may be selectedwhen the clinician is finished viewing activity graph 288.

The quantified number of posture state changes may be an indicator ofthe effectiveness of stimulation therapy. Greater numbers of posturechanges per day may indicate that therapy is successful because thetherapy is allowing patient 12 to be engaged in a variety of posturesand activities. In the example of FIG. 16A, patient 12 has increasedtheir average number of posture state changes from 23 per day in Marchto 61 per day in June to indicate at least somewhat successful therapy.A reduction in the number of posture state changes per day may indicatethat the therapy is no longer effective in treating the condition ofpatient 12. In other examples, activity graph 288 may presentinformation identifying the particular therapy programs or groups ofprograms used during the respective time interval to correlate thetherapies with posture state change information. This type ofcorrelation may assist the clinician in narrowing in on the appropriatetherapy parameters to treat patient 12.

FIG. 16B is a flow diagram illustrating an example method for presentingan average quantified number of posture changes during selected timeintervals of therapy. In the example of FIG. 16B, posture state module86 senses the posture states in which patient 12 engages while IMD 14delivers stimulation therapy to patient 12 (301). Processor 80 thenstores the sensed posture states as a plurality of posture state datawithin memory 82 of IMD 14 (303). If there is no request from the userto view an activity graph (305), IMD 14 continues to sense posturestates and deliver therapy to patient 12 (301). If user interface 106 ofexternal programmer 60 receives a request from the user to present theactivity graph (305), then processor 104 acquires the posture state datafrom IMD 14 via telemetry circuit 110 (307). In other examples,processor 104 may first acquire posture state data from IMD 14 during aroutine communication session and then acquire the posture state datafrom memory 108 of external programmer 20 when required to display theactivity graph.

Once processor 104 has access to the posture state data, processor 104determines the time intervals that will be used for the activity graph(309). The time intervals may be a therapy session, day, week, month,customized durations, or any other durations requested by the user orpredetermined by processor 104. Processor 104 then analyzes the posturestate data in order to calculate the average number of posture changesof each day in the determined time intervals (311). If the activitygraph should include the numerical value of the changes in addition tothe activity bars (313), processor 104 generates the activity graph withactivity bars and numerical values for each time interval (315). If theactivity graph is not to include the numerical value (313), processor104 generates the activity graph with only the activity bars (317). Inother examples, processor 104 may present only the numerical values ofthe average posture changes.

Once processor 104 generates the appropriate activity graph, userinterface 106 presents the activity graph to the user via externalprogrammer 20 (319). System 10 then continues to sense posture stateswhile delivering therapy to patient 122 (301). In other examples, theactivity graph may be presented by any local or networked externaldevice.

FIG. 17 is a conceptual diagram illustrating an example user interface208 for presenting sleep quality information as a graph of thequantified number of posture state changes when the patient is lyingdown. In general, presentation of sleep quality information may includeobtaining posture state data sensed by a medical device for a patient,and generating sleep quality information based on lying posture statechanges (e.g., transitions among lying front, lying back, lying rightand lying left) indicated by the posture state data. The sleep qualityinformation can then be presented to a user via a user interface.

As shown in FIG. 17, screen 298 of user interface 208 presents sleepquality information via sleep quality graph 300 and done button 310. Asmentioned previously, the clinician may select sleep quality button 242to navigate to screen 298. In other words, processor 104 may presentscreen 298 once the sleep quality input is received from the clinician.Screen 298 also provides done button 310 to return the clinician to theprevious screen of the user interface. Alternatively, the clinician maybe able to access sleep quality graph 300 via a separate menu itemwithin user interface 208.

Sleep quality graph 300 may assist the clinician, and even patient 12,in determining how therapy aids the quality of sleep. Sleep qualitygraph 300 includes change bars 302 to graphically represent the numberof lying posture changes and change values 304 to numerically representthe number of lying posture changes. In addition, time intervals 306show that each interval is a non-consecutive day. More lying downposture changes are indicative of restlessness or continued symptomsthat interrupt deep sleep. For example, on Jun. 13, 2008 (“06/13/2008”),patient 12 made 26 changes to their lying down posture state. However,by Jun. 19, 2008 (“06/19/2008), patient 12 only made 15 changes to theirposture state when lying down. This may indicate to the clinician thatpatient 12 is responding to effective stimulation therapy. In someexamples, sleep quality graph 300 may include an association to theparticular stimulation program or group of programs used to delivertherapy. The clinician may be able to determine which programs or groupsare most effective at allowing patient 12 to sleep during the night.

Detail input note 308 informs the clinician to “Click on each bar fordetails.” If the clinician clicks or selects a sleep quality bar withinsleep quality graph 300, processor 104 presents the number of differenttransitions from each lying posture or the number of transitions betweeneach of the lying down postures.

IMD 14 may detect sleep by detecting consecutive lying down posturesthat indicate patient 12 is attempting to sleep. However, tracking lyingdown postures may not be an accurate indication of actual sleep ofpatient 12 because the patient may not actually be sleeping when lyingdown. Therefore, some embodiments of IMD 14 may monitor a physiologicalparameter of patient 12 in addition to tracking lying down postures. Forexample, posture state module 86, or a separate module, may include aphysiological sensor that detects changes within patient 12 indicativeof sleep. The physiological sensor may include electrodes, pressuresensors, accelerometers, or other sensors capable of detecting heartrate, breathing rate, electroencephalograph (EEG) signals, eye movement,or any other physiological parameter that may aid clinician programmer60 in determining when patient 12 is actually asleep. As an alternative,or further feature, sleep quality may be detected based in part by atime of day such that lying posture changes during normal sleeping hoursfor the patient are tracked to indicate sleep quality. For example,lying posture changes occurring between 10 P.M. and 6 A.M. could betracked to provide an indication of sleep quality.

In the example of FIG. 17, sleep quality is generally expressed in termsof the number of lying posture changes in a time interval. Additionally,or alternatively, the percentage of time in which the patient occupieseach lying posture (lying back, lying front, lying right, lying left)may be presented. In this manner, the clinician may observe thepatient's predominant sleeping position and changes in the positionduring the course of the night. As a further refinement, IMD 14 orexternal programmer 30 may track specific transitions from one lyingposture to another, e.g., lying back to lying left, or vice versa,and/or time spent in particular postures, to evaluate relative patientdiscomfort in different postures.

FIG. 18 is a conceptual diagram illustrating an example user interface208 for presenting details on the number of times patient 12 movedbetween each posture state during sleep associated with FIG. 17. Asshown in FIG. 18, screen 312 of user interface 208 provides heading 314,time intervals 316, and detailed posture state data 320 that includesthe number of changes from each posture state to a different posturestate. Heading 314 describes the posture state data presented in screen312. Posture state transitions 322 indicates the specific posture statetransitions and change quantity 324 is the number of times patient 12performed that posture state transition in a time interval. Intervalindicator 318 encircles the time interval “06/16/2008” because that isthe time interval that the clinician selected to view posture state data320 in the example of FIG. 18. The clinician can then select ShowBarChart button 326 to navigate back to the sleep quality graph 300 inorder to view the sleep quality information from the multiple timeintervals.

As described with reference to FIGS. 17 and 18, the sleep qualityinformation may include sleep quality information for each of aplurality of time intervals. The sleep quality information for each ofthe time intervals may indicates a number of changes from a plurality ofdifferent lying posture states during the respective time interval. Forexample, the sleep quality information may indicate a number of changesfrom each of a plurality of different lying posture states during a timeinterval. In particular, the sleep quality information may indicate anumber of changes from each of a plurality of different lying posturestates to each of the other lying posture states during a time interval.

The clinician may desire to view the specific posture state data touncover which posture state transitions 322 occur most frequently. Inparticular, screen 312 may present the number of transitions for eachspecific lying posture state transition. Examples of lying posture statetransitions, as shown in FIG. 18, include back to right, back to left,back to front, front to back, front to right, front to left, right toback, right to front, right to left, left to back, left to front, andleft to right. The number of times each transition was made by a patientduring the time interval may be presented as shown in FIG. 18. Morefrequent changes away from a certain posture state may indicate adeficiency with the therapy to treat patient 12 in that posture. Morefrequent changes to a certain posture may indicate that therapy iseffective in that posture, or that the posture is desired by the patient12. This specific transition information may be accompanied by postureduration information or other information that may be useful inevaluating sleep quality and therapeutic efficacy for different lyingposture states that may be associated with sleep. In any case, posturestate data 320 may allow the clinician to monitor various consistenciesor abnormalities among the lying posture habits of patient 12.

FIG. 19 is a conceptual diagram illustrating an example user interface208 for presenting the average number of posture state changes whenpatient 12 is lying down for a given month. Screen 328 may besubstantially similar to screen 298 of FIG. 17, but screen 328 presentsaveraged numbers of posture changes for a given month. In otherexamples, screen 328 may present therapy sessions as the time intervalinstead of months. As shown in FIG. 19, screen 328 of user interface 208presents sleep quality information via sleep quality graph 330 and donebutton 340. As mentioned previously, the clinician may select sleepquality button 242 to navigate to screen 330. In other words, processor104 presents screen 328 once the sleep quality input is received fromthe clinician. Screen 328 also provides done button 340 to return theclinician to the previous screen of the user interface. Alternatively,the clinician may be able to access sleep quality graph 330 via aseparate menu item within user interface 208.

Sleep quality graph 330 may assist the clinician, and even patient 12,in determining how therapy aids the quality of sleep as trends overtime. Sleep quality graph 330 includes change bars 332 to graphicallyrepresent the average number of lying posture changes per day within thetime interval and change values 334 to numerically represent the averagenumber of lying posture changes per day. In addition, time intervals 336show that each interval is a consecutive month. The trends suggested bysleep quality graph 330 is that patient 12 slept better during March andJune than April or May. This may indicate to the clinician that patient12 is responding to recent change in stimulation therapy, or that theclinician should revert to using previously used stimulation parameters.In some examples, sleep quality graph 330 may include an association tothe particular stimulation program or group of programs used to delivertherapy.

Similar to FIG. 17, detail input note 338 informs the clinician to“Click on barchart for details.” If the clinician clicks or selects asleep quality bar within sleep quality graph 330, processor 104 presentsthe average number of times patient 12 left each of the posture statesper day within the time interval.

FIG. 20 is a conceptual diagram illustrating an example user interface208 for presenting detailed information on the average number of timespatient 12 left each lying posture. Screen 342 is similar to screen 312of FIG. 18. However, screen 342 only presents the average number oftimes each day patient 12 left each posture state. As shown in FIG. 20,screen 312 of user interface 208 provides heading 344, time intervals346, posture states 348A, 348B, 348C, and 348D (collectively “posturestates 348”), and associated leave values 350A, 350B, 350C, and 350D(collectively “leaving values 350”). Return button 352 allows theclinician to return to the sleep quality graph 330 of FIG. 19.

Heading 344 describes the posture state data presented in screen 342,which are the average number of times patient 12 left each posturestate. For each of posture states 348, screen 342 presents the averagenumber of times that patient 12 left each of the respective posturestates, irrespective of the posture state to which patient 12transitioned. Leaving values 350 are averages for the time interval,which may be rounded to the nearest whole leaving value. From the numberof times that patient left each posture state, the clinician may be ableto determine for which posture state 348 therapy is not effective whenpatient 12 lying down and attempting to sleep. For example, the timeinterval of May shows that patient 12 moved from the lying on their backposition an average of eleven times a day. This may be excessive andindicate that patient 12 is getting little quality sleep. The cliniciancan then select return button 352 to navigate back to the sleep qualitygraph 330 in order to view the sleep quality information from themultiple time intervals.

FIG. 21 is a conceptual diagram illustrating an example user interface208 for presenting the average number of posture state changes when thepatient is lying down during each therapy session. Screen 343 may besubstantially similar to screen 328 of FIG. 19, However, screen 343presents averaged numbers of posture changes for a given therapy sessionas the time interval. As shown in FIG. 21, screen 343 of user interface208 presents sleep quality information via sleep quality graph 345.Change bars 349 graphically represent the average number of lyingposture changes per day within the time interval and change values 347numerically represent the average number of lying posture changes perday.

The time intervals for each of change bars 349 and change values 347 areprovided as therapy sessions. Each therapy session is identified by thestart date to the therapy session and the end date of the therapysession, typically determined by the date patient 12 visits a clinic fora programming session to review stimulation therapy efficacy and makeparameter or program adjustments to therapy. Clinic leave dates 351provide the start date for each of the four therapy sessions provided byscreen 343, e.g., 12/29/2008 to represent Dec. 29, 2008. Clinic arrivedates 353 provide the end dates for each the four therapy sessions,e.g., 02/099/2009 to represent Feb. 9, 2009. Each therapy session may beas short as a day or as long as several months to several years.Although screen 343 may provide consecutive therapy sessions, otherexamples of screen 343 may provide only certain nonconsecutive therapysessions depending upon the sleep quality information desired by theuser or the sleep quality information most appropriate to review thetherapy efficacy for patient 12.

FIG. 22 is a flow diagram illustrating an example method for presentingproportional posture information to the user from recently storedposture state data. The method of FIG. 22 will be directed to clinicianprogrammer 60 as an example, but any external programmer 20 or computingdevice may perform these methods. As shown in FIG. 22, user interface208 receives proportional posture input from the user, e.g., theclinician (354). The proportional posture input may be a request,entered via user interface, for presentation of proportional postureinformation. Processor 104 then acquires posture state data, e.g., fromIMD 14 (356). Alternatively, processor 104 may acquire the posture statedata from another device, such as patient programmer 30, additionalsensors, or any other device that communicates with IMD 14 or a sensorof the system.

Processor 104 of programmer 60 may interrogate IMD 14 by wirelesstelemetry to retrieve such information. All of the information may bestored in IMD 14. Alternatively, programmer 60 may obtain only recentinformation from IMD 14, such as information obtained by IMD 14 sincethe last interrogation, and rely on information stored in the programmerfrom previous interrogations. Hence, the information may includeinformation stored in programmer 60 from previous interrogations of IMD14 and information freshly acquired from IMD 14. In some examples,processor 104 may reject any raw posture state data from short therapysessions, when one or more therapy sessions are shorter than the sessionthreshold, e.g., twenty-four hours. In this case, processor 104 maygenerate posture state output, such as sleep quality information orproportional posture information, based on the raw posture state datathat is not rejected. Although processor 104 may simply not use therejected posture state data this one time, processor 104 may also deleteany raw posture state data that was rejected.

Next, processor 104 generates the posture duration graph in order tographically present the posture state data to the user (358). Generatingthe posture duration graph may involve some graphical rendering orotherwise creating the graphical representation of the posture statedata. Processor 104 then presents the posture duration graph via userinterface 208 (360), e.g., as shown in FIG. 11.

If user interface 208 does not receive detail input signaling the user'sdesire to view the detailed posture state data (362), processor 104continues to present the posture duration graph (360). If user interface208 receives the detail input (362), then processor 104 presents thedetailed posture state data via user interface 208 (364), e.g., as shownin FIG. 12. Upon receiving the return input to view the posture durationgraph (366), processor 104 again presents the posture duration graph(360).

FIG. 23 is a flow diagram illustrating an example method for presentingspecific proportional posture information to the user on the postureduration graph. The method of FIG. 23 will be directed to clinicianprogrammer 60 as an example, but any external programmer 20 or computingdevice may perform these methods. As shown in FIG. 23, processor 104first acquires posture state data from IMD 14, for example (368). Next,processor 104 averages posture durations and the number of transitions aday for the determined time intervals (370). The segment duration ofeach time interval may be preselected or customized by the clinician. Inthe method of FIG. 23, processor 104 acquires the posture state data andperforms the necessary calculations on the posture state data before theproportional posture information is requested by the clinician. Whilethis may not need to be performed in this manner, it may allow forfaster transitions for the clinician when navigating through userinterface 208. In some examples, processor 104 may reject any rawposture state data from short sessions, when one or more sessions areshorter than the session threshold, e.g., twenty-four hours. Althoughprocessor 104 may simply not use the rejected posture state data thisone time, processor 104 may also permanently delete any raw posturestate data that was rejected.

Once user interface 208 receives the proportional posture inputrequesting the posture duration graph (372), processor 104 checks ifpercentage information is to be presented (374). If the percentage oftime for each posture state is to be presented (374), then processor 104adds the percentage information to the posture duration graph (376).Otherwise, processor 104 determines if the posture state frequency valueshould be added to the posture duration graph (378). If the posturestate frequency value is to be added, processor 104 adds the posturestate frequency value to the posture duration graph (380). Finally,processor 104 presents the proportional posture information in the formof the posture duration graph via user interface 208 (382).

FIG. 24 is a flow diagram illustrating an example method for presentingsleep quality information derived from the posture state data for a dayor over a month time interval. Again, the method of FIG. 24 will bedirected to clinician programmer 60 as an example, but any externalprogrammer 20 or computing device may perform these methods. As shown inFIG. 24, processor 104 acquires posture state data from IMD 14, memory108, or a combination of the two (384). Alternatively, processor 104 mayacquire the posture state data from another device, such as patientprogrammer 30, additional sensors, such as externally worn sensors, orany other device that communicates with IMD 14 or a sensor of thesystem. Upon receiving the sleep quality input from the clinician (386),processor 104 then determines if the data needs to be averaged over themonth segment duration of the time interval (388). If no averaging isneeded because the sleep quality graph will be presented with day timeintervals, the processor 104 generates the number of lying posturechanges for each time interval (392). Otherwise, processor 104 averagesthe number of lying posture changes (390). As explained above, the timeinterval may be of any duration, and the time intervals do not need tobe of equivalent durations. For example, the time intervals may betherapy sessions defined by when patient 12 visits the clinic.

Processor 104 next presents the sleep quality information as a sleepquality graph via user interface 208 (394). Upon receiving a detailinput from the clinician (396), processor 104 presents detailed sleepquality information (398). As described in FIGS. 18 and 20, the detailedsleep quality information may be the number of each posture transitionor the number of times patient 12 left each posture state. Processor 104returns to the sleep quality graph once user interface 208 receives thereturn input from the clinician (400). In alternative examples,clinician programmer 60 may require additional steps in order to providecustomizable graphical information to the clinician or provide dataflexibility.

FIG. 25 is a flow diagram illustrating an example method for rejectingraw posture state data stored during a session shorter than a sessionduration. The method of rejecting raw posture state data will bedescribed with regard to clinician programmer 60, but any externalprogrammer 20 may be configured to similarly reject posture state data.As shown in FIG. 25, processor 104 of clinician programmer 60 acquiresraw posture state data from IMD 14 (402). Next, processor 104 determinesif any of the raw posture state data was stored during a session thatwas shorter than the session threshold (404).

Each session may be a therapy session corresponding to time betweenprogramming sessions, a time between changes in therapy parameters, anactive therapy duration in which therapy was delivered to the patient,or some other manner to determine differences in therapy. Theprogramming sessions may be successive programming sessions performed insuccessive clinic visits, or programming sessions performed in the sameclinic visit. The therapy session threshold may be set according to thedesires of the clinician, the behavior of patient 12, or dynamicallyaccording to the course of therapy. Therefore, the session threshold maybe one hour, twenty four hours, one week, or one month, for example.Additionally, the session threshold may be set to a percent of thelongest session duration or percent of the average session duration inwhich raw posture data was stored. For example, the session thresholdmay be set to less than ten percent of a session duration of the longestsession duration in which raw posture state data was stored.

As an illustration, posture state data stored when less than twenty fourhours elapsed between programming sessions, e.g., between clinicianvisits by the patient, may be rejected because of this short therapysession. Posture state information obtained when therapy parametervalues are applied for only a short therapy session may not be relied,relative to posture state information obtained for therapy parametervalues applied over a longer period of time. In some cases, a patientmay leave a clinic and then return the next day to readjust parametersdue to lack of efficacy or discomfort, resulting in a short therapysession. As another example, a short therapy session may result when theclinician is interrupted during a programming session. In each case, toavoid adding unreliable data from the short session, or possiblyoverwriting good data with new data from the short therapy session,posture state information obtained during the short therapy session canbe rejected, e.g., discarded rather than stored.

If processor 104 determines that there were no short sessions (404),processor 104 keeps all of the raw posture state data (406) andgenerates posture state output, such as sleep quality information orproportional posture information. If one or more sessions are shorterthan the session threshold (404), processor 104 rejects any raw posturestate data from these short sessions (408). Although processor 104 maysimply not use the rejected posture state data this one time, processor104 may also delete any raw posture state data that was rejected.Finally, processor 104 generates posture state output from the remainingposture state data that was not rejected (410). As examples, thegenerated posture state output may be sleep quality information orproportional posture information. Other types of posture state outputmay be generated based on the remaining posture state data that was notrejected.

FIG. 26A is a conceptual diagram illustrating an example user interface208 for presenting an adjustment graph 416 that displays a number oftherapy adjustments 418 made by patient 12 in a time interval. Forexample, adjustment graph 416 may display the average number of therapyadjustments made by patient 12 when entering into a different posturestate. FIG. 26B is a conceptual diagram illustrating an example userinterface 208 for presenting an adjustment graph 415 that displays anabsolute number of therapy adjustments that patient 12 makes whileoccupying a posture state during a time interval. FIG. 26C is aconceptual diagram illustrating an example user interface 208 forpresenting an adjustment graph 427 that displays an average number oftherapy adjustments that patient 12 makes each time the patient occupiesa posture state during a time interval. FIG. 26D is a conceptual diagramillustrating an example user interface 208 for presenting an adjustmentgraph 427 that displays a total number of therapy adjustments thatpatient 12 makes for all posture states during a time interval. Ingeneral, according to the examples of FIGS. 26A-D, a programmer 20 orIMD 14 determines the number of patient adjustments to posturestate-responsive therapy delivered to patient 12 over a time interval.Although FIGS. 26A-26D present therapy adjustment information in agraphical form for purposes of illustration, the therapy adjustmentinformation may be presented in other ways, such as in text or acombination of graphics and text.

FIG. 26A illustrates the tracking of an average number of initialadjustments made by patient 12 each time the patient moves to aparticular posture state, e.g., within an initial adjustment periodfollowing sensing of the posture state, during a time interval. FIG. 26Billustrates the tracking of an absolute number of adjustments made whilepatient 12 has occupied a particular posture state during a timeinterval. Alternatively, FIG. 26C illustrates the tracking of an averagenumber of adjustments made by patient 12 each time the patient occupiesa given posture state. In some cases, the number of therapy adjustmentsmade by patient 12 for all posture states may be tracked and presented,as illustrated in FIG. 26D. In general, in the examples of FIGS.26A-26C, IMD 14 may associate therapy adjustments received from patient12 with posture states occupied by the patient. In the example of FIG.26D, however, it may not be necessary to associate therapy adjustmentswith individual posture states.

In each of the examples of FIGS. 26A-26D, the number of patient therapyadjustments may provide objective information that can be used by aclinician to evaluate efficacy of therapy delivered to the patient whenthe patient makes the therapy adjustments. The therapy may be posturestate-responsive therapy that applies different therapy parameteraccording to the posture state occupied by patient 12. Tracking andpresenting the number of patient therapy adjustments, such as initialadjustments per posture state, all adjustments per posture state, or alladjustments for all posture states, may provide an objective indicationof the efficacy of the parameters presently being deliveredautomatically according to the posture state-responsive therapy or afixed therapy. As described below, the number of patient therapyadjustments may be expressed as an average number per posture or a totalnumber per posture, in a given time interval.

As shown in FIG. 26A, screen 412 of user interface 208 presents theaverage number of initial therapy adjustments patient 12 makes each timepatient 12 changes to a particular posture state. A patient therapyadjustment may be made by a patient by selecting or adjusting one ormore parameter values for a current program, e.g., via a patientprogrammer. For example, an adjustment may be made to one or more of anamplitude, a pulse width, a pulse rate, an electrode combination, or anelectrode polarity. In addition, a therapy adjustment may be entered bypatient 12 simply selecting a different therapy program to determine thestimulation therapy that is applied. In response to a patient therapyadjustment, IMD 14 may apply the patient therapy adjustment to therapythat is delivered to the patient 12. However, IMD 14 may apply thepatient therapy adjustment on a temporary basis while patient 12 residesin the posture state. The next time that patient 12 occupies the posturestate, IMD 14 may again apply the existing therapy parameters for theposture state according to the established posture state-responsivetherapy programming. In this case, patient 12 may again enter patienttherapy adjustments, if desired or necessary to achieve better efficacy.

The therapy adjustments may be made by patient 12 to modify one or moreparameters of therapy delivered in a posture state-responsive therapymode in order to enhance efficacy. Again, analysis of the number oftherapy adjustments by a clinician may provide objectificationinformation about the efficacy of the parameters presently appliedaccording to the posture state-responsive therapy delivery during thetherapy session. For example, a large number of patient adjustments totherapy parameters may indicate that the level of therapeutic efficacyprovided by existing therapy parameters is insufficient. A small numberof adjustments may provide an objective indication that existing therapyparameters support better therapeutic efficacy. A clinician may evaluatethe number of adjustments in considering whether the existing therapy isacceptable, or whether clinician adjustments to posture state-responsivetherapy parameters are advisable. If the number of patient therapyadjustments is tracked for individual posture states, the clinician mayadjust parameters for each individual posture state. If the number ofpatient therapy adjustments is tracked on an overall basis for allposture states, the clinician may evaluate adjustments to parametersrelating to various posture states to provide an overall modification ofthe therapy.

In some cases, therapy adjustments by patient 12 may be made more oftenat the beginning of therapy, e.g., in earlier therapy sessions, becauseeffective therapy has not yet been established. Over time, however,therapy parameters may be better optimized as the clinician makesadjustments to posture state-responsive therapy parameters in laterprogramming sessions, e.g., based in part on analysis of objectiveefficacy information such as the number of patient therapy adjustmentsmade overall or for particular postures. As discussed above, duringdelivery of posture-state responsive therapy, IMD 14 may modify therapyparameters based on patient therapy adjustments to allow IMD 14 tobetter anticipate what amplitude should be used for each posture state.A clinician may later analyze the number of patient therapy adjustmentsin order to evaluate possible adjustments to posture state-responsivetherapy.

In screen 412 of FIG. 26A, the clinician may review graph 416 todetermine how many times patient 12 has needed to adjust therapyparameters in each posture state, on average, during a time interval,such as a day, week, month or therapy session. In the example of FIG.26A, graph 416 presents an average of initial patient therapyadjustments for a given posture state in each of plurality of monthlytime intervals. A patient 12 may occupy each posture state multipletimes in a given time interval. Hence, the average number of patientadjustments for a posture state may be the average number of patientadjustments each time the patient occupies the posture state, i.e., foreach instance of the posture state. In the example of FIG. 26A, theclinician may select the desired posture state from posture state menu414, e.g., the lying (back) posture state. Then, user interface 208presents adjustment graph 416 that includes therapy adjustments 418 andadjustment bars 420 for each of the time intervals 422.

The average number of initial adjustments for a given posture state foreach time interval may be displayed simultaneously in screen 412 withthe average number of initial adjustments for the given posture forother time intervals, so that a trend may be observed over several timeintervals, such as several therapy sessions with different therapyparameters. In the example of FIG. 26A, patient 12 has needed to makefewer initial adjustments, on average, as therapy has progressed fromearlier therapy sessions to later therapy sessions, and has only changedtherapy twice when moving to the lying back posture, on average, in themost recent time interval. The clinician may select return button 424 toreturn to the previous screen or to navigate to a menu screen of userinterface 208.

The therapy adjustments tracked in FIG. 26A are initial adjustments inthe sense that they are adjustments made in an initial adjustment periodas patient 12 enters the new posture, rather than adjustments that aremade later. Evaluation of initial therapy adjustments may be useful inidentifying difficulty in achieving effective therapy upon moving to anew posture state. For example, patient 12 may need to make severalchanges to amplitude when moving from an upright posture state to alying back posture state because IMD 14 may not be initially programmedto sufficiently accommodate for the change in posture state. FIG. 26Apresents an average number of initial therapy adjustments made for agiven posture state each time the patient 12 assumes that posture statein a given time interval, such as a therapy session. As an alternative,user interface 208 may present a cumulative number of initial therapyadjustments made by patient 12 for all instances of a given postureduring a time interval. As a further alternative, user interface 208 maypresent a cumulative number of initial adjustments for all posturestates during a time interval.

FIG. 26B presents an absolute number of patient therapy adjustmentsreceived for a particular posture state during a given time interval,such as a therapy session. Instead of only initial adjustments receivedduring an initial adjustment period, the adjustments presented in FIG.26B may include the number of all patient therapy adjustments receivedwhile the patient resides in the pertinent posture state during a timeinterval. The patient therapy adjustments may represent adjustmentsneeded for the patient to reach a desired level of efficacy for theposture state. A greater number of patient adjustments may indicate thatthe patient has greater difficulty in achieving a desired level ofefficacy for a posture state, given posture-state responsive therapyparameters initially applied when the posture state is sensed. Hence, atotal number of patient therapy adjustments for multiple instances of aparticular posture state may indicate efficacy of posturestate-responsive therapy for that posture state. In some cases, acumulative number of patient therapy adjustments for all posture statesmay provide an indication of overall efficacy of the posturestate-responsive therapy.

With reference to FIG. 26B, using screen 415, a clinician may select adesired posture state from posture state menu 414, e.g., the lying(back) posture state. Then, user interface 208 presents adjustment graph417 that includes therapy adjustments 418 and adjustment bars 420 foreach of the time intervals 422. In FIG. 26B, the number of adjustmentsfor all instances of a given posture state for each time interval may bedisplayed simultaneously with the number of adjustments for allinstances of the given posture for other time intervals, so that a trendmay be observed over several time intervals, such as several therapysessions with different therapy parameters. In the example of FIG. 26B,as in the example of FIG. 26A, patient 12 has needed to make fewerinitial adjustments as therapy has progressed from earlier therapysessions to later therapy sessions. The clinician may select returnbutton 424 to return to the previous screen or to navigate to a menuscreen of user interface 208.

The number of patient therapy adjustments presented to a user may betracked and presented in a variety of ways. For example, the number ofpatient therapy adjustments presented to a user by user interface 208may be an absolute number of patient therapy adjustments received forall instances of a given posture during a time interval, as indicated inFIG. 26B. As an alternative, user interface 208 may present an averagenumber of patient therapy adjustments received for a given posture eachtime patient 12 assumes the posture during a time interval, i.e., foreach instance of a posture state. Screen 421 of FIG. 26C shows anadjustment graph 421 that presents the average number of patientadjustments (“Average adjustments for posture”) each time a patient 12enters a posture state in a given time interval. As a furtheralternative, user interface 208 may present a cumulative number ofpatient therapy adjustments received for all postures during a timeinterval. Screen 423 of FIG. 26D shows an adjustment graph 425 thatpresents a cumulative number of patient therapy adjustments (“Totaladjustments for all postures”) during different time intervals. In theexample of FIG. 26D, it may not be necessary to associate patienttherapy adjustments with particular posture states. Rather, IMD 14 maysimply count the number of patient therapy adjustments in a timeinterval.

With further reference to FIG. 26A, determination of which therapyadjustments are to be categorized as initial therapy adjustmentsassociated with entry into a posture state during an initial adjustmentperiod may be accomplished by using an adjustment period timer. Inparticular, an adjustment period timer may be used to reject therapyadjustments that are not clearly associated with initial entry into aparticular posture state. The adjustment timer may start when a newposture state is detected and last for an adjustment period. Theadjustment period may last for generally 10 seconds to 60 minutes. Morespecifically, the adjustment period may be between 30 seconds and 5minutes. In some examples, the adjustment period may be approximately 3minutes. During the adjustment period, IMD 14 or patient programmer 30,may associate each therapy adjustment with the current posture state andquantify the associations. The quantified number of initial therapyadjustments may then be reviewed by patient 12 or the clinician.

For example, patient 12 may transition from the upright posture state tothe lying back posture state. The adjustment timer starts when IMD 14detects the new lying back posture state, and the adjustment period isset to 3 minutes. In the first 3 minutes that patient 12 is engaged inthe lying back posture state, each patient therapy adjustment toamplitude (or other parameters) is counted and stored as the patienttherapy adjustments needed for that lying back posture state. Patienttherapy adjustments made after expiration of the adjustment period arenot counted as initial therapy adjustments, and can be disregarded inthe count for purposes of the example of FIG. 26A. Since the number oftherapy adjustments may change in time, e.g., as a clinician adjustsposture state-responsive therapy, the clinician may review thisinformation over a series of time intervals between programming sessionsin which posture state-responsive therapy parameters are adjusted by theclinician to determine how therapy is anticipating the desired therapyparameters of patient 12. A user such as a clinician could view a graphvia a programmer or other device that shows the number of initialtherapy adjustments made by the patient due to posture change. Forexample, if there was a therapy adjustment, e.g., to amplitude, duringan adjustment period between a time a therapy adjustment is made and atime the adjustment can be attributed to a particular posture state, thetherapy adjustment could be characterized as an adjustment due toposture change and counted as such. Then, a number of adjustments due toposture change could be presented graphically as an actual number oraverage number within a time period, such as a day, week, month, therapysession, or the like. The number of adjustments may provide anindication of how often the patient needs to use the programmer tomanually adjust therapy for a posture change, and how comfortable thepatient is with stimulation after the posture change, thereby providinginformation that may be useful in programming IMD 14.

Patient therapy adjustments may be associated with a particular posturestate if they are received while patient 12 occupies the posture state,i.e., following detection of a given posture and before detection of adifferent posture state. To limit analysis to initial patient therapyadjustments in some implementations, an adjustment period may beapplied, as described above. As a further alternative, in some examples,IMD 14 or programmer 20 may be configured to associate patient therapyadjustments with posture states using a posture search timer and posturestability timer. In particular, IMD 14 or programmer 20 may implement aposture search timer and a posture stability timer for each instance ofpatient therapy adjustment, i.e., each time a therapy adjustment isreceived from patient 12. The posture search timer and posture stabilitytimer may be used, for example, to associate patient therapy adjustmentswith posture states for purposes of the examples of FIGS. 26A-26C.

The posture search timer may have a search period and a posturestability timer may have a stability period that, when used together,allow the system to associate a patient therapy adjustment to a posturestate. If the patient therapy adjustment is associated with a posturestate, then it can be counted as a patient therapy adjustment for theposture state as in the examples of FIGS. 26A and 26B. If initialtherapy adjustments are tracked according to FIG. 26A, an adjustmentperiod also may be applied, in addition to the search timer and thestability timer, to identify initial therapy adjustments. For example,if a patient therapy adjustment satisfies both the search timer and thestability timer, the adjustment period timer still may be applied toreject patient therapy adjustments that were not entered in an initialadjustment period, which may run in parallel with the search andstability periods. For the examples of FIGS. 26B-26D, however, aninitial adjustment period is not necessary because all patient therapyadjustments are tracked, instead of just initial therapy adjustments.

In general, the search timer starts each time a patient therapyadjustment is received by programmer 20 or by IMD 14 via programmer 20.The stability timer starts each time a posture state is sensed after apatient therapy adjustment is received. If the stability timer startswithin the search period, and the posture state remains stable for theduration of the stability timer, then the patient therapy adjustment canbe associated with the posture state and counted. Patient 12 may occupya posture state multiple times such that there are multiple instances ofthe sensed posture state. Each time patient 12 occupies the posturestate, the patient may enter one or more patient therapy adjustments.Hence, the multiple therapy adjustments may be obtained over multipleinstances of the sensed posture state, and associated with the posturestate according to the search timer and stability timer, producing acumulative count for the posture state, e.g., as indicated in theexample of FIG. 26B. Alternatively, therapy adjustments may be countedseparately for separate instances of posture states so that an averagenumber of adjustments per posture state can be determined, e.g.,according to the example of FIG. 26C.

In some examples, clinician programmer 60 may allow the clinician toadjust the search period of the posture search timer and the stabilityperiod of the posture stability timer. The posture search timer and theposture stability timer enable IMD 14 to determine the posture statewith which a therapy adjustment should be associated. Depending upon thecondition of patient 12 or clinician preferences, the clinician maydesire to adjust the search period and stability period to accuratelyreflect the intentions of patient 12. For example, if patient 12 has ahabit of adjusting therapy long before making a change to the posturestate or patient 12 takes a long time to assume a desired posture state,the clinician may desire to increase the search period and stabilityperiod in order to properly associate the therapy adjustment with theintended posture state. In some examples, clinician programmer 60 maysuggest appropriate search periods and stability periods for patientsdiagnosed with particular conditions that may hinder their movement orinvolve multiple oscillations in posture state before settling on thefinal posture state.

The search timer starts upon receipt of a patient therapy adjustment.According to one example, in order to associate a therapy adjustmentwith a posture state, the stability timer for the posture state muststart before the end of the search period, and the posture state mustnot change during the stability period, i.e., the posture state mustremain stable. Therefore, the search period and stability period mustoverlap for the therapy adjustment to be associated with a posture statethat is not currently occupied by patient 12 when the therapy adjustmentwas made.

Generally, the search period may be between approximately 30 seconds and30 minute minutes, but it may be set to any time desired, including atime that is outside of that range. More specifically, the search periodmay be between approximately 30 seconds and 5 minutes, or morepreferably 2 minutes to 4 minutes in order to provide a reasonableamount of time for patient 12 to be situated in the final desiredposture state. In some examples, the search period is approximately 3minutes. In other cases, shorter search periods may be used, e.g.,approximately 1 second to 60 seconds, or approximately 5 seconds to 20seconds.

In addition, the stability period may be of any time duration desired bythe manufacturer or clinician. Generally, the stability period isbetween approximately 30 seconds and 30 minutes, but it may be set toany time desired, including times outside of that range. Morespecifically, the stability period may be between approximately 30seconds and 5 minutes, and more preferably 2 minutes to 4 minutes, inorder to ensure that patient 12 is situated in the final desired posturestate for a reasonable amount of time and that the final posture stateis not just some transitional or interim posture state. In someexamples, the stability period is approximately 3 minutes. Although thesearch period and stability period may have the same duration, they maybe different in other examples. In other cases, shorter stabilityperiods may be used, e.g., approximately 1 second to 60 seconds, orapproximately 5 seconds to 20 seconds.

FIG. 27 is a conceptual diagram illustrating an example user interface208 for presenting a table 429 that displays the number of initialtherapy adjustments 434 the patient makes when entering into a differentposture state. Again, the overall number or average number of therapyadjustments made by the patient for a posture state could be presentedinstead of only the initial therapy adjustments, e.g., as indicated inFIGS. 26B and 26C. Alternatively, the overall number of therapyadjustments for all posture states could be presented, e.g., as in theexample of FIG. 26D. FIG. 27 is similar to FIG. 26A, except that thenumber of therapy adjustments are shown numerically and for severalposture state. As shown in FIG. 27, screen 426 of user interface 208presents header 428, time intervals 430, table 429, posture states 432A,432B, 432C, and 432D (collectively “posture states 432”), therapyadjustments 434A, 434B, 434C, and 434D (collectively “therapyadjustments 434”), and barchart button 436. Again, a representationsimilar to that of FIG. 27 could be used to display the number oftherapy adjustments or average number of therapy adjustments for eachposture state in a time interval, as in the examples of FIGS. 26B and26C.

Header 428 describes the information presented in screen 426, i.e., thatscreen 426 provides the average initial adjustments for each posturestate. Time intervals 430 are the time in therapy to which the presentedinformation relates, and time intervals 430 are shown in consecutivemonths. Table 429 provides the average number of therapy adjustments 434for each posture state 432. Although only four posture states 432 areshown, screen 426 may provide any or all of the posture states used byIMD 14. In addition, the clinician may select barchart button 436 toview a graphical representation of table 429, similar to adjustmentgraph 416 of FIG. 26A.

FIG. 28A is a flow diagram illustrating an example method for presentingthe number of therapy adjustments made in response to entering a newposture state. As shown in FIG. 28, IMD 14 delivers therapy to patient12 according to groups of programs (438). Once IMD 14 detects thatpatient 12 enters a new posture state (440), processor 80 of IMD 14starts the adjustment timer to track any initial therapy adjustmentsentered by patient 12 (442). Processor 80 then counts each therapyadjustment made by patient 12 during the adjustment period (444).Processor 80 then stores the number of therapy adjustments made for thatposture state (446) and continues to deliver therapy (438). In someexamples, processor 104 of patient programmer 30 may track and store thetherapy adjustments made by patient 12. Processor 80 may store thenumber of therapy adjustments as a cumulative number for all instancesof the posture state, i.e., all times that the patient 12 occupied theposture state during a given time interval. Alternatively, processor 80may store a separate count for each instance of the posture state in thetime interval, so that user interface 208 may present an average numberof therapy adjustments for each time the patient 12 entered the posturestate.

FIG. 28B is a flow diagram illustrating an example method for presentingthe number of therapy adjustments that a patient makes while occupying aposture state. In the example of FIG. 28A, processor 80 of IMD 14determines a posture state of patient 12 (450), and delivers therapy tothe patient (452), e.g., with parameters selected according to theposture state in order to support posture state-responsive therapy.While the patient resides in the posture state, processor 80 determineswhether a patient therapy adjustment has been received (454). If not,processor 80 updates the posture state (450) and delivers therapy (442).If a patient therapy adjustment is received (454), processor 80 countsthe therapy adjustment and associates it with the posture state (456),or an instance of the posture state, and then returns to repeat thedetermination of posture state (450) and delivery of therapy to thepatient (452). In some examples, to associate a therapy adjustment witha posture state, IMD 14 may apply search and stability timers.

Again, the patient therapy adjustment count may be counted cumulativelyfor all instances of the posture state during a time interval, orcounted for each instance of the posture state individually, i.e., foreach time patient 12 assumes the posture state. In this manner, thenumber of patient therapy adjustments may be counted as an absolutenumber, or an average number for each time the patient assumes theposture state. As a further alternative, in some examples, processor 80may track a cumulative count of all patient therapy adjustments for allposture state over a therapy interval, e.g., as an overall indication ofefficacy. The examples of FIGS. 28A and 28B are provided for purposes ofillustration. Other techniques for tracking and presenting the number ofpatient therapy adjustment may be implemented.

FIGS. 29-33 illustrate examples of the application of a search timer andstability timer to associate patient therapy adjustments with posturestates so that a total or average number of adjustments may be trackedfor different posture states over different time intervals. FIG. 29 is aconceptual diagram illustrating example posture search timer 550 andposture stability timer 552 when patient 12 remains in one posturestate. As described in this disclosure, in some examples, IMD 14 must beable to correctly associate each therapy adjustment with a therapyparameter to the intended posture state of patient 12 when the therapyadjustment was made. For example, patient 12 may make therapyadjustments to customize the therapy either after patient 12 moves to adifferent posture state or in anticipation of the next posture state.IMD 14 may employ posture search timer 550 and posture stability timer552 to track therapy adjustments and the current posture state ofpatient 12. Although IMD 14 may associate therapy adjustments of anytherapy parameter to a posture state, some examples of IMD 14 may onlyallow the association of amplitude changes. In this manner, patient 12may change different therapy parameters such as pulse width, pulse rate,or electrode configuration, but IMD 14 will not store these therapyadjustments as being associated to any posture state in some examples.

Posture search timer 550 has a search period that is a set amount oftime that patient 12 has from the time the therapy adjustment is made,when posture search timer 550 starts, to when the final posture statemust begin, prior to the expiration of the search period. In otherwords, in this example, the patient therapy adjustment will not beassociated with a posture state entered after the search period hasexpired. In addition, posture stability timer 552 has a stability periodthat is a set amount of time that patient 12 must remain within thefinal posture state for the therapy adjustment made to be associatedwith the final posture state. Posture stability timer 552 restarts atany time that patient 12 changes posture states. In order to associate atherapy adjustment with a posture state, the stability timer for theposture state must start before the end of the search period, and theposture state must not change during the stability period. Therefore,the search period and stability period must overlap for the therapyadjustment to be associated with a posture state not currently engagedby patient 12 when the therapy adjustment was made.

In the example of FIG. 29, patient 12 made a therapy adjustment to oneof the therapy parameters, such as voltage or current amplitude, at timeT₀. Therefore, posture search timer 550 starts at T₀ and runs for apredetermined search period until time T₁. When the therapy adjustmentis made, posture stability timer 552 also starts at time T₀ in thecurrent posture state of patient 12 and runs for the stability period.In the example of FIG. 29, the stability period is the same as thesearch period. Since patient 12 has not changed to any different posturestates between times T₀ and T₁, the stability period also ends at T₁.The therapy adjustment made by patient 12 at time T₀ is associated withthe posture state sensed between times T₀ and T₁ because both the searchperiod and stability period overlap. In the example of FIG. 29, posturesearch timer 550 and posture stability timer 552 may not be needed, buttheir purpose may become clearer in the following examples.

The search period of posture search timer 550 may be of any timeduration desired by a device manufacturer, and the clinician may or maynot be permitted to set the search period to a desired value or within apredetermined search range. Generally, the search period may be betweenapproximately 30 seconds and 30 minute minutes, but it may be set to anytime desired, including a time that is outside of that range. Morespecifically, the search period may be between approximately 30 secondsand 5 minutes, or more preferably 2 minutes to 4 minutes in order toprovide a reasonable amount of time for patient 12 to be situated in thefinal desired posture state. In some examples, and as described in theexamples of FIGS. 29-33, the search period is approximately 3 minutes.In other cases, shorter search periods may be used, e.g., approximately1 second to 60 seconds, or approximately 5 seconds to 20 seconds.

In addition, the stability period of posture stability timer 552 may beof any time duration desired by the manufacturer or clinician, where theclinician may or may not be permitted to set the stability period.Generally, the stability period is between approximately 30 seconds and30 minutes, but it may be set to any time desired, including timesoutside of that range. More specifically, the stability period may bebetween approximately 30 seconds and 5 minutes, and more preferably 2minutes to 4 minutes, in order to ensure that patient 12 is situated inthe final desired posture state for a reasonable amount of time and thatthe final posture state is not just some transitional or interim posturestate. In some examples, and as described in the examples of FIGS.29-33, the stability period is approximately 3 minutes. Although thesearch period and stability period may have the same duration, they maybe different in other examples. In other cases, shorter stabilityperiods may be used, e.g., approximately 1 second to 60 seconds, orapproximately 5 seconds to 20 seconds.

As described herein, associating therapy adjustments with intendedposture states allow the user to review the number of therapyadjustments made by patient 12 while assuming, or transitioning to, eachposture state. The number of therapy adjustments may be used forobjectification of efficacy of existing therapy delivered to patient 12.

FIG. 30 is a conceptual diagram illustrating example posture searchtimer 554 and posture stability timer 556 with one change in posturestate. As shown in FIG. 30, patient 12 makes an anticipatory therapyadjustment for the next posture state that patient 12 does not currentlyoccupy. In other words, patient 12 makes a therapy adjustment that thepatient may believe is desirable for a given posture in anticipation oftransitioning to that posture on an imminent or near-term basis. Posturesearch timer 554 and posture stability timer 556 start at time T₀ whenpatient 12 makes a therapy adjustment in a current posture stateoccupied at time T₀. At time T₁, patient 12 changes to a second posturestate that is different than the initial posture state occupied at timeT₀. Therefore, posture stability timer 556 restarts at time T₁, with thechange to the new posture state, still within the search duration ofposture search timer 554.

In some implementations, patient therapy adjustments received during thesearch period restart the search period. As a result, a series ofpatient therapy adjustments that are entered closely in time are, ineffect, clustered together such that intermediate adjustments are notcounted for the posture state. Instead, the last adjustment in a seriesof closely spaced (in time) adjustments is associated with the posturestate to represent the final adjustment that brought the parameter to alevel or value deemed appropriate by the patient 12 for the givenposture state. If the search period is three minutes, for example, andthe patient 12 makes four adjustments in voltage amplitude within threeminutes of one another, e.g., 4.6 volts to 4.8 volts, 4.8 volts to 5.0volts, 5.0 volts to 5.1 volts, 5.1 volts to 5.3 volts, then the finaladjustment value of 5.3 volts may be associated with the posture state.

Each time a new adjustment is entered within the search period, thesearch period is reset. Once the final adjustment is made, however, ifthere are no further adjustments for another three minutes, and thestability period is satisfied for the detected posture state, then thefinal adjustment is associated with the posture state. Clustering of anumber of patient therapy adjustments can be useful in order to presenta series of closely timed adjustments as a single programmingintervention event. Treatment of clustered adjustments as a singleprogramming intervention event may be especially appropriate if thevalues of the adjustments are also close to one another.

Time T₂ indicates the end of posture search timer 554. Consequently, theonly posture state that processor 80 of IMD 14 will associate with thetherapy adjustment is the second posture state as long as the secondposture state satisfies the stability period of posture stability timer556, i.e., the patient occupies the second posture state for thestability period. At time T₃, patient 12 is still in the second posturewhen the stability period ends, and the therapy adjustment is associatedthen to the second posture state because the stability period overlappedwith the search period.

It should be noted that patient 12 may make additional therapyadjustments within the search period. If this occurs, any previoustherapy adjustments made before the search period or stability period iscompleted are not associated to any posture state. Therefore, both thesearch period and stability period must lapse, i.e., expire, in orderfor a therapy adjustment to be associated with a posture state. However,in some examples, IMD 14 may allow therapy adjustments to be associatedwith posture states as long as the search period has lapsed or nodifferent posture state was sensed during the search period.

FIG. 31 is a conceptual diagram illustrating example posture searchtimer 550 and posture stability timer 560 with two changes in posturestates. As shown in FIG. 31, patient 12 makes an anticipatory therapyadjustment but is engaged in an interim posture state before settlinginto the final posture state. Posture search timer 558 and posturestability timer 560 both start at time T₀ when patient 12 makes atherapy adjustment in a current posture state engaged at time T₀.

At time T₁, patient 12 changes to a second posture state, or an interimposture state, that is different than the initial posture state engagedat time T₀. Therefore, posture stability timer 560 restarts at time T₁,still within the search duration of posture search timer 558. At timeT₂, patient 12 changes to a third posture state, and again posturestability timer 560 restarts. Time T₃ indicates the end of posturesearch timer 558, so the only posture state that processor 80 of IMD 14will associate with the therapy adjustment is the third posture statebegun at time T₂ as long as the third posture state satisfies thestability period of posture stability timer 560. At time T₄, patient 12is still in the third posture when the stability period ends, and thetherapy adjustment is associated then to the third and final posturestate because the stability period of the third posture state overlappedwith the search period.

FIG. 32 is a conceptual diagram illustrating example search timer 562and posture stability timer 564 with the last posture state changeoccurring outside of the posture search timer. As shown in FIG. 32,patient 12 makes an anticipatory therapy adjustment but is engaged in aninterim posture state too long before settling into the final posturestate for the therapy adjustment to be associated with any posturestate. Posture search timer 562 and posture stability timer 564 bothstart at time T₀ when patient 12 makes a therapy adjustment in a currentposture state engaged at time T₀. At time T₁, patient 12 changes to asecond posture state, or an interim posture state, that is differentthan the initial posture state engaged at time T₀. Therefore, posturestability timer 564 restarts at time T₁, still within the searchduration of posture search timer 562.

However, the search timer expires at time T₂, before patient 12 changesto a third posture state at time T₃, when posture stability timer 564again restarts. The stability period for the third posture state thenexpires at time T₄. Since the third posture state did not start beforethe search period expired at time T₂, the search period and stabilityperiod do not overlap and the therapy adjustment from time T₀ is notassociated to any posture state. In other examples, therapy adjustmentsmay still be associated with the posture state occupied at time T₀ whenthe search period and last stability period do not overlap.

The following is a further illustration of the example described in FIG.32 to put the example in context of an example patient scenario. Patient12 may be engaged in the upright posture state when patient 12 makes thetherapy adjustment at time T₀. In this example, the search duration isthree minutes and the stability duration is also three minutes. Aftertwo minutes, or at time T₁, patient 12 transitions to the lying leftposture to cause processor 80 of IMD 14 to restart posture stabilitytimer 560.

If patient 12 remains within the lying left posture for the full threeminutes of the stability duration, then the therapy adjustment would beassociated with the lying left posture. However, patient 12 leaves thelying left posture after only two minutes, or at time T₃, outside of thesearch duration. At this point the therapy amplitude made at time T₀,will not be associated for the next posture state of patient 12.Therefore, the next posture state may be the lying back posture state.Once IMD 14 senses the lying back posture state, IMD 14 may changetherapy according to the therapy parameters associated with the lyingback posture because IMD 14 is operating in the automatic posturestate-responsive mode. No new associations with the therapy adjustmentwould be made in the example of FIG. 32.

FIG. 33 is a flow diagram illustrating an example method for associatinga received therapy adjustment with a posture state. Although the exampleof FIG. 17 will be described with respect to patient programmer 30 andIMD 14, the technique may be employed in any external programmer 20 andIMD or other computing device. As shown in FIG. 17, user interface 106receives the therapy adjustment from patient 12 (566) and processor 80of IMD 14 immediately starts the posture search timer (568) and theposture stability timer (570).

If the posture state of patient 12 does not change (572), processor 80checks to determine if the stability period has expired (576). If thestability period has not expired (576), processor 80 continues to sensefor a posture state change (572). If the stability period has expired(576), processor 80 uses the final posture state, i.e., the currentlysensed posture state, to select therapy parameters to deliver therapy(582). Processor 80 then associates the therapy adjustment with thefinal posture state and counts the therapy adjustment for that posturestate (584).

If processor 80 senses a posture state change (572), processor 80determines if the search period has expired (574). If the search periodhas not expired (574), then processor 80 restarts the posture stabilitytimer (570). If the search period has expired (574), then processor 80automatically delivers posture state-responsive therapy to patient 12according to the current posture state (578). Processor 80 does notassociate the patient therapy adjustment with the final posture statebecause the search period did not overlap with the stability period(580).

In some examples, as an alternative, a posture stability timer may beemployed without the use of a posture search timer. As described withrespect to posture stability timer 560, the posture stability timer maybe started after a therapy adjustment and reset each time patient 12changes posture states prior to expiration of the posture stabilitytimer. When the posture stability timer 560 expires, the therapyadjustment may be associated with the posture state that patient 12 isoccupying at that time. In this manner, the therapy adjustment may beassociated with the first stable posture state, i.e., the first posturestate that remains stable for the duration of the posture stabilitytimer, after the therapy adjustment, regardless of the amount of timethat has past since the therapy adjustment. Hence, in someimplementations, processor 80 may apply only a stability timer without asearch timer.

In some example implementations, processor 80 may not change posturestate-responsive therapy to patient 12 until the stability periodexpires. In this case, the posture stability timer may run independentlyof the posture search timer to track posture states independently oftherapy adjustments. Therefore, in some cases, IMD 14 may not performautomatic posture responsive stimulation until the posture state ofpatient 12 is stable and the stability period has expired. In thismanner, patient 12 may not be subjected to rapidly changing therapy whentransitioning between multiple posture states. Alternatively, IMD 14 mayemploy a separate posture stability timer for changing therapy duringautomatic posture state-responsive therapy from the therapy adjustmentrelated posture stability timer as described in this disclosure.

This disclosure may provide multiple features to a user. For example, aclinician may quickly review the posture states engaged by the patientduring stimulation therapy to assess therapy efficacy. Sleep qualityinformation may be viewed to identify the number of times the patient ischanging posture states during sleep. Proportional posture informationmay be viewed to identify how long patient 12 engages in each types ofposture due to the therapy being delivered. In this manner, theclinician may be able to identify posture state trends with patient 12and make adjustments to therapy parameters as needed to continuallyincrease the effectiveness of stimulation therapy. Further, posturestate data stored during short sessions may be rejected from use ingenerating posture state information.

In accordance with various aspects of this disclosure, a medical devicesystem may support sleep quality monitoring based on transitions betweendifferent posture states, e.g., lying back, lying front, lying left,lying right, upright, during a sleep period to objectively evaluatesleep quality. Transitions between different lying posture states may beparticularly useful in evaluating sleep quality. In addition, trackingvarious parameters such as different posture states, amount of timespent in different posture states, percentage of time in differentposture states, averages, ranges, or other trending data or statisticalmeasures for presentation to a clinician may support objectification ofpatient condition and patient response to therapy.

In addition, a medical device system may present information relating tothe number of posture state changes assumed by a patient in a timeinterval and the number of patient therapy adjustments made by a patienta time interval. The number of patient therapy adjustments made by apatient may provide an indication of a level of efficacy provided byposture state-responsive therapy. If the patient has made a large numberof adjustments, a clinician may infer that posture state-responsivetherapy should be adjusted to provide a higher level of efficacy. Insome cases, the number of patient therapy adjustments may be monitoredfor each of the posture states, such that efficacy of the posturestate-responsive therapy may be evaluated for each posture state. Thenumber of patient therapy adjustments may be presented as an absolutenumber or an average number of adjustments for a given time interval. Insome cases, the number of patient therapy adjustments may be a number oraverage number of initial adjustments made within an adjustment periodfollowing a posture state change.

Various aspects of the techniques described in this disclosure may beimplemented within an IMD, an external programmer, or a combination ofboth. Moreover, in some embodiments, information may be processed by theIMD, programmer or a dedicated processing device such as a networkserver. For example, posture state information may be stored in raw formin an IMD and retrieved from the IMD by an external programmer or otherexternal device for generation of proportional posture informationand/or sleep quality information. Alternatively, the IMD may process theposture state information at least partially for retrieval by anexternal device. In some cases, an IMD may be configured to generateproportional posture information and/or sleep quality information forretrieval by an external device. Accordingly, the particularimplementations described in this disclosure are presented for purposesof illustration and without limitation as to the techniques broadlydescribed in this disclosure.

The techniques described in this disclosure may be implemented, at leastin part, in hardware, software, firmware or any combination thereof. Forexample, various aspects of the techniques may be implemented within oneor more microprocessors, digital signal processors (DSPs), applicationspecific integrated circuits (ASICs), field programmable gate arrays(FPGAs), or any other equivalent integrated or discrete logic circuitry,as well as any combinations of such components, embodied in programmers,such as physician or patient programmers, stimulators, or other devices.The term “processor” or “processing circuitry” may generally refer toany of the foregoing logic circuitry, alone or in combination with otherlogic circuitry, or any other equivalent circuitry.

When implemented in software, the functionality ascribed to the systemsand devices described in this disclosure may be embodied as instructionson a computer-readable medium such as random access memory (RAM),read-only memory (ROM), non-volatile random access memory (NVRAM),electrically erasable programmable read-only memory (EEPROM), FLASHmemory, magnetic media, optical media, or the like. The instructions maybe executed to support one or more aspects of the functionalitydescribed in this disclosure.

In addition, it should be noted that the systems described herein maynot be limited to treatment of a human patient. In alternativeembodiments, these systems may be implemented in non-human patients,e.g., primates, canines, equines, pigs, and felines. These animals mayundergo clinical or research therapies that my benefit from the subjectmatter of this disclosure.

Many embodiments of the invention have been described. Variousmodifications may be made without departing from the scope of theclaims. These and other embodiments are within the scope of thefollowing claims.

1. A method comprising: sensing posture states of a patient; deliveringposture-state responsive electrical stimulation therapy to the patientbased on the sensed posture states; receiving patient adjustments to theelectrical stimulation therapy delivered to the patient; determining anumber of the patient adjustments received over a time interval; andpresenting a representation of the number of the patient adjustmentsreceived over the time interval to a user.
 2. The method of claim 1,wherein determining a number of the patient adjustments comprisesdetermining a number of the patient adjustments for each of the sensedposture states.
 3. The method of claim 2, wherein: determining comprisesdetermining a number of the patient adjustments received for each of thesensed posture states over a plurality of time intervals; and presentingcomprises presenting a representation of the number of the patientadjustments received for each of the sensed posture states over each ofthe plurality of time intervals to a user via a user interface.
 4. Themethod of claim 3, wherein presenting comprises presentingrepresentations of the numbers of the patient adjustments received foreach of the sensed posture states over each of the plurality of timeintervals simultaneously.
 5. The method of claim 3, wherein determininga number of the patient adjustments comprises determining an averagenumber of the patient adjustments for each of the posture states foreach time that the patient occupies the respective posture state in eachof the time intervals, and wherein the representation includes theaverage number of the patient adjustments.
 6. The method of claim 2,wherein determining a number of the patient adjustments comprisesdetermining an average number of the patient adjustments for each of theposture states for each time that the patient occupies the respectiveposture state in the time interval, and wherein the representationincludes the average number of the patient adjustments.
 7. The method ofclaim 6, wherein determining a number of the patient adjustments foreach of the posture states for each time that the patient occupies therespective posture state in the time interval comprises determining anaverage number of the patient adjustments made within an adjustmenttimer period following sensing of the respective posture state.
 8. Themethod of claim 2, further comprising delivering the electricalstimulation therapy to the patient via an implantable medical device,wherein the posture state-responsive electrical stimulation therapy hasone or more parameters that are specified according to the sensedposture states.
 9. The method of claim 2, further comprising: sensingthe posture states of the patient in an implantable medical device;determining the number of the patient adjustments in one of a processorof the implantable medical device or a processor of an externalprogrammer; and presenting the representation of the number of thepatient adjustments via a user interface of the external programmer. 10.A system comprising: a sensor that senses posture states of a patient; astimulation generator that delivers posture-state responsive electricalstimulation therapy to the patient based on the sensed posture states;an input device that receives patient adjustments to the electricalstimulation therapy delivered to the patient; a processor thatdetermines a number of the patient adjustments received over a timeinterval; and a user interface that presents a representation of thenumber of the patient adjustments received over the time interval to auser via a user interface.
 11. The system of claim 10, wherein theprocessor determines a number of the patient adjustments for each of thesensed posture states.
 12. The system of claim 11, wherein: theprocessor determines a number of the patient adjustments received foreach of the sensed posture states over a plurality of time intervals;and the user interface presents a representation of the number of thepatient adjustments received for each of the sensed posture states overeach of the plurality of time intervals to a user via a user interface.13. The system of claim 12, wherein the user interface presentsrepresentations of the numbers of the patient adjustments received foreach of the sensed posture states over each of the plurality of timeintervals simultaneously.
 14. The system of claim 12, wherein theprocessor determines an average number of the patient adjustments foreach of the posture states for each time that the patient occupies therespective posture state in each of the time intervals, and wherein therepresentation includes the average number of the patient adjustments.15. The system of claim 11, wherein the processor determines an averagenumber of the patient adjustments for each of the posture states foreach time that the patient occupies the respective posture state in thetime interval, and wherein the representation includes the averagenumber of the patient adjustments.
 16. The system of claim 15, whereinthe processor determines the average number as an average number of thepatient adjustments made within an adjustment timer period followingsensing of the respective posture state.
 17. The system of claim 11,wherein the posture state-responsive electrical stimulation therapy hasone or more parameters that are specified according to the sensedposture states.
 18. The system of claim 11, wherein: the sensor thatsenses the posture includes a sensor in an implantable medical device;the processor that determines the number of the patient adjustments isone of a processor of the implantable medical device or a processor ofan external programmer; and the user interface that presents therepresentation of the number of the patient adjustments is a userinterface of the external programmer.
 19. A system comprising: means forsensing posture states of a patient; means for delivering posture-stateresponsive electrical stimulation therapy to the patient based on thesensed posture states; means for receiving patient adjustments to theelectrical stimulation therapy delivered to the patient; means fordetermining a number of the patient adjustments received over a timeinterval; and means for presenting a representation of the number of thepatient adjustments received s over the time interval to a user.
 20. Thesystem of claim 19, wherein the means for determining a number of thepatient adjustments comprises means for determining a number of thepatient adjustments for each of the sensed posture states.
 21. Thesystem of claim 20, wherein: the means for determining comprises meansfor determining a number of the patient adjustments received for each ofthe sensed posture states over a plurality of time intervals; and themeans for presenting comprises means for presenting a representation ofthe number of the patient adjustments received for each of the sensedposture states over each of the plurality of time intervals to a uservia a user interface.
 22. The system of claim 21, wherein the mean forpresenting comprises means for presenting representations of the numbersof the patient adjustments received for each of the sensed posturestates over each of the plurality of time intervals simultaneously. 23.The system of claim 21, wherein the means for determining a number ofthe patient adjustments comprises means for determining an averagenumber of the patient adjustments for each of the posture states foreach time that the patient occupies the respective posture state in eachof the time intervals, and wherein the representation includes theaverage number of the patient adjustments.
 24. The system of claim 21,wherein the means for determining a number of the patient adjustmentscomprises means for determining an average number of the patientadjustments for each of the posture states for each time that thepatient occupies the respective posture state in the time interval, andwherein the representation includes the average number of the patientadjustments.
 25. The system of claim 24, wherein the means fordetermining a number of the patient adjustments for each of the posturestates for each time that the patient occupies the respective posturestate in the time interval comprises means for determining an averagenumber of the patient adjustments made within an adjustment timer periodfollowing sensing of the respective posture state.
 26. The system ofclaim 21, wherein the a posture state-responsive electrical stimulationtherapy has one or more parameters that are specified according to thesensed posture states.
 27. The system of claim 21, further comprising:means for sensing the posture states of the patient in an implantablemedical device; means for determining the number of the patientadjustments in one of a processor of the implantable medical device or aprocessor of an external programmer; and means for presenting therepresentation of the number of the patient adjustments via a userinterface of the external programmer.